Halomethylated high performance curable polymers

ABSTRACT

Disclosed is a process which comprises the steps of (a) providing a polymer containing at least some monomer repeat units with halomethyl group substituents which enable crosslinking or chain extension of the polymer upon exposure to a radiation source which is electron beam radiation, x-ray radiation, or deep ultraviolet radiation, said polymer being of the formula ##STR1## wherein x is an integer of 0 or 1, A is one of several groups as specified in the claims, B is one of several groups as specified in the claims, and n is an integer representing the number of repeating monomer units, and (b) causing the polymer to become crosslinked or chain extended through the photosensitivity-imparting groups. Also disclosed is a process for preparing a thermal ink jet printhead by the aforementioned curing process.

BACKGROUND OF THE INVENTION

The present invention is directed to improved curable compositions. Morespecifically, the present invention is directed to curablehalomethylated polymer compositions and to improved photoresistcompositions and improved thermal ink jet printheads containing thesepolymers. One embodiment of the present invention is directed to aprocess which comprises the steps of (a) providing a polymer containingat least some monomer repeat units with halomethyl group substituentswhich enable crosslinking or chain extension of the polymer uponexposure to a radiation source which is electron beam radiation, x-rayradiation, or deep ultraviolet radiation, said polymer being of theformula ##STR2## wherein x is an integer of 0 or 1, A is ##STR3## ormixtures thereof, B is ##STR4## wherein v is an integer of from 1 toabout 20, ##STR5## wherein z is an integer of from 2 to about 20,##STR6## wherein u is an integer of from 1 to about 20, ##STR7## whereinw is an integer of from 1 to about 20, ##STR8## or mixtures thereof, andn is an integer representing the number of repeating monomer units, and(b) causing the polymer to become crosslinked or chain extended throughthe photosensitivity-imparting groups. Another embodiment of the presentinvention is directed to a process which comprises the steps of:

(a) depositing a layer comprising a polymer of the above formula onto alower substrate in which one surface thereof has an array of heatingelements and addressing electrodes having terminal ends formed thereon,said polymer being deposited onto the surface having the heatingelements and addressing electrodes thereon;

(b) exposing the layer to a radiation source which is electron beamradiation, x-ray radiation, or deep ultraviolet radiation in animagewise pattern such that the polymer in exposed areas becomescrosslinked or chain extended and the polymer in unexposed areas doesnot become crosslinked or chain extended, wherein the unexposed areascorrespond to areas of the lower substrate having thereon the heatingelements and the terminal ends of the addressing electrodes;

(c) removing the polymer from the unexposed areas, thereby formingrecesses in the layer, said recesses exposing the heating elements andthe terminal ends of the addressing electrodes;

(d) providing an upper substrate with a set of parallel grooves forsubsequent use as ink channels and a recess for subsequent use as amanifold, the grooves being open at one end for serving as dropletemitting nozzles; and

(e) aligning, mating, and bonding the upper and lower substratestogether to form a printhead with the grooves in the upper substratebeing aligned with the heating elements in the lower substrate to formdroplet emitting nozzles, thereby forming a thermal ink jet printhead.Yet another embodiment of the present invention is directed to specificpolymeric compositions within the above formula.

In microelectronics applications, there is a great need for lowdielectric constant, high glass transition temperature, thermallystable, photopatternable polymers for use as interlayer dielectriclayers and as passivation layers which protect microelectroniccircuitry. Poly(imides) are widely used to satisfy these needs; thesematerials, however, have disadvantageous characteristics such asrelatively high water sorption and hydrolytic instability. There is thusa need for high performance polymers which can be effectivelyphotopatterned and developed at high resolution.

One particular application for such materials is the fabrication of inkjet printheads. Ink jet printing systems generally are of two types:continuous stream and drop-on-demand. In continuous stream ink jetsystems, ink is emitted in a continuous stream under pressure through atleast one orifice or nozzle. The stream is perturbed, causing it tobreak up into droplets at a fixed distance from the orifice. At thebreak-up point, the droplets are charged in accordance with digital datasignals and passed through an electrostatic field which adjusts thetrajectory of each droplet in order to direct it to a gutter forrecirculation or a specific location on a recording medium. Indrop-on-demand systems, a droplet is expelled from an orifice directlyto a position on a recording medium in accordance with digital datasignals. A droplet is not formed or expelled unless it is to be placedon the recording medium.

Since drop-on-demand systems require no ink recovery, charging, ordeflection, the system is much simpler than the continuous stream type.There are different types of drop-on-demand ink jet systems. One type ofdrop-on-demand system has as its major components an ink filled channelor passageway having a nozzle on one end and a piezoelectric transducernear the other end to produce pressure pulses. The relatively large sizeof the transducer prevents close spacing of the nozzles, and physicallimitations of the transducer result in low ink drop velocity. Low dropvelocity seriously diminishes tolerances for drop velocity variation anddirectionality, thus impacting the system's ability to produce highquality copies. Drop-on-demand systems which use piezoelectric devicesto expel the droplets also suffer the disadvantage of a slow printingspeed.

The other type of drop-on-demand system is known as thermal ink jet, orbubble jet, and produces high velocity droplets and allows very closespacing of nozzles. The major components of this type of drop-on-demandsystem are an ink filled channel having a nozzle on one end and a heatgenerating resistor near the nozzle. Printing signals representingdigital information originate an electric current pulse in a resistivelayer within each ink passageway near the orifice or nozzle, causing theink in the immediate vicinity to vaporize almost instantaneously andcreate a bubble. The ink at the orifice is forced out as a propelleddroplet as the bubble expands. When the hydrodynamic motion of the inkstops, the process is ready to start all over again. With theintroduction of a droplet ejection system based upon thermally generatedbubbles, commonly referred to as the "bubble jet" system, thedrop-on-demand ink jet printers provide simpler, lower cost devices thantheir continuous stream counterparts, and yet have substantially thesame high speed printing capability.

The operating sequence of the bubble jet system begins with a currentpulse through the resistive layer in the ink filled channel, theresistive layer being in close proximity to the orifice or nozzle forthat channel. Heat is transferred from the resistor to the ink. The inkbecomes superheated far above its normal boiling point, and for waterbased ink, finally reaches the critical temperature for bubble formationor nucleation of around 280° C. Once nucleated, the bubble or watervapor thermally isolates the ink from the heater and no further heat canbe applied to the ink. This bubble expands until all the heat stored inthe ink in excess of the normal boiling point diffuses away or is usedto convert liquid to vapor, which removes heat due to heat ofvaporization. The expansion of the bubble forces a droplet of ink out ofthe nozzle, and once the excess heat is removed, the bubble collapses.At this point, the resistor is no longer being heated because thecurrent pulse has passed and, concurrently with the bubble collapse, thedroplet is propelled at a high rate of speed in a direction towards arecording medium. The surface of the printhead encounters a severecavitational force by the collapse of the bubble, which tends to erodeit. Subsequently, the ink channel refills by capillary action. Thisentire bubble formation and collapse sequence occurs in about 10microseconds. The channel can be refired after 100 to 500 microsecondsminimum dwell time to enable the channel to be refilled and to enablethe dynamic refilling factors to become somewhat dampened. Thermal inkjet equipment and processes are well known and are described in, forexample, U.S. Pat. No. 4,601,777, U.S. Pat. No. 4,251,824, U.S. Pat. No.4,410,899, U.S. Pat. No. 4,412,224, U.S. Pat. No. 4,532,530, and U.S.Pat. No. 4,774,530, the disclosures of each of which are totallyincorporated herein by reference.

The present invention is suitable for ink jet printing processes,including drop-on-demand systems such as thermal ink jet printing,piezoelectric drop-on-demand printing, and the like.

In ink jet printing, a printhead is usually provided having one or moreink-filled channels communicating with an ink supply chamber at one endand having an opening at the opposite end, referred to as a nozzle.These printheads form images on a recording medium such as paper byexpelling droplets of ink from the nozzles onto the recording medium.The ink forms a meniscus at each nozzle prior to being expelled in theform of a droplet. After a droplet is expelled, additional ink surges tothe nozzle to reform the meniscus.

In thermal ink jet printing, a thermal energy generator, usually aresistor, is located in the channels near the nozzles a predetermineddistance therefrom. The resistors are individually addressed with acurrent pulse to momentarily vaporize the ink and form a bubble whichexpels an ink droplet. As the bubble grows, the ink bulges from thenozzle and is contained by the surface tension of the ink as a meniscus.The rapidly expanding vapor bubble pushes the column of ink filling thechannel towards the nozzle. At the end of the current pulse the heaterrapidly cools and the vapor bubble begins to collapse. However, becauseof inertia, most of the column of ink that received an impulse from theexploding bubble continues its forward motion and is ejected from thenozzle as an ink drop. As the bubble begins to collapse, the ink stillin the channel between the nozzle and bubble starts to move towards thecollapsing bubble, causing a volumetric contraction of the ink at thenozzle and resulting in the separation of the bulging ink as a droplet.The acceleration of the ink out of the nozzle while the bubble isgrowing provides the momentum and velocity of the droplet in asubstantially straight line direction towards a recording medium, suchas paper.

Ink jet printheads include an array of nozzles and may, for example, beformed of silicon wafers using orientation dependent etching (ODE)techniques. The use of silicon wafers is advantageous because ODEtechniques can form structures, such as nozzles, on silicon wafers in ahighly precise manner. Moreover, these structures can be fabricatedefficiently at low cost. The resulting nozzles are generally triangularin cross-section. Thermal ink jet printheads made by using theabove-mentioned ODE techniques typically comprise a channel plate whichcontains a plurality of nozzle-defining channels located on a lowersurface thereof bonded to a heater plate having a plurality of resistiveheater elements formed on an upper surface thereof and arranged so thata heater element is located in each channel. The upper surface of theheater plate typically includes an insulative layer which is patternedto form recesses exposing the individual heating elements. Thisinsulative layer is referred to as a "pit layer" and is sandwichedbetween the channel plate and heater plate. For examples of printheadsemploying this construction, see U.S. Pat. No. 4,774,530 and U.S. Pat.No. 4,829,324, the disclosures of each of which are totally incorporatedherein by reference. Additional examples of thermal ink jet printheadsare disclosed in, for example, U.S. Pat. No. 4,835,553, U.S. Pat. No.5,057,853, and U.S. Pat. No. 4,678,529, the disclosures of each of whichare totally incorporated herein by reference.

The photopatternable polymers prepared by the process of the presentinvention are also suitable for other photoresist applications,including other microelectronics applications, printed circuit boards,lithographic printing processes, interlayer dielectrics, and the like.

U.S. Pat. No. 3,914,194 (Smith), the disclosure of which is totallyincorporated herein by reference, discloses a formaldehyde copolymerresin having dependent unsaturated groups with the repeating unit##STR9## wherein R is an aliphatic acyl group derived from saturatedacids having 2 to 6 carbons, olefinically unsaturated acids having 3 to20 carbons, or an omega-carboxy-aliphatic acyl group derived fromolefinically unsaturated dicarboxylic acids having 4 to 12 carbons ormixtures thereof, R₁ is independently hydrogen, an alkyl group of 1 to10 carbon atoms, or halogen, Z is selected from oxygen, sulfur, thegroup represented by Z taken with the dotted line representsdibenzofuran and dibenzothiophene moieties, or mixtures thereof, n is awhole number sufficient to give a weight average molecular weightgreater than about 500, m is 0 to 2, p and q have an average value of 0to 1 with the proviso that the total number of p and q groups aresufficient to give greater than one unsaturated group per resinmolecule. These resins are useful to prepare coatings on varioussubstrates or for potting electrical components by mixing with reactivediluents and curing agents and curing.

"Chloromethylation of Condensation Polymers Containing anoxy-1,4-phenylene Backbone," W. H. Daly et al., Polymer Preprints, Vol.20, No. 1, 835 (1979), the disclosure of which is totally incorporatedherein by reference, discloses the chloromethylation of polymerscontaining oxy-phenylene repeat units to produce film forming resinswith high chemical reactivity. The utility of 1,4-bis(chloromethoxy)butane and 1-chloromethoxy-4-chlorobutane as chloromethylating agentsare also described.

European Patent Application EP-0,698,823-A1 (Fahey et al.), thedisclosure of which is totally incorporated herein by reference,discloses a copolymer of benzophenone and bisphenol A which was shown tohave deep ultraviolet absorption properties. The copolymer was founduseful as an antireflective coating in microlithography applications.Incorporating anthracene into the copolymer backbone enhanced absorptionat 248 nm. The encapper used for the copolymer varied depending on theneeds of the user and was selectable to promote adhesion, stability, andabsorption of different wavelengths.

M. Camps, M. Chatzopoulos, and J. Montheard, "Chloromethyl Styrene:Synthesis, Polymerization, Transformations, Applications," JMS--Rev.Macromol. Chem. Phys., C22(3), 343-407 (1982-3), the disclosure of whichis totally incorporated herein by reference, discloses processes for thepreparation of chloromethyl-substituted polystyrenes, as well asapplications thereof.

Y. Tabata, S. Tagawa, and M. Washio, "Pulse Radiolysis Studies on theMechanism of the High Sensitivity of Chloromethylated Polystyrene as anElectron Negative Resist," Lithography, 25(1), 287 (1984), thedisclosure of which is totally incorporated herein by reference,discloses the use of chloromethylated polystyrene in resistapplications.

M. J. Jurek, A. E. Novembre, I. P. Heyward, R. Gooden, and E.Reichmanis, "Deep UV Photochemistry of Copolymers ofTrimethyl-Silylmethyl Methacrylate and Chloromethylstyrene," PolymerPreprints, 29(1) (1988), the disclosure of which is totally incorporatedherein by reference, discloses the use of an organosilicon polymer ofchloromethylstyrene for resist applications.

P. M. Hergenrother, B. J. Jensen, and S. J. Havens, "Poly(aryleneethers)," Polymer, 29, 358 (1988), the disclosure of which is totallyincorporated herein by reference, discloses several arylene etherhomopolymers and copolymers prepared by the nucleophilic displacement ofaromatic dihalides with aromatic potassium bisphenates. Polymer glasstransition temperatures ranged from 114° to 310° C. and some weresemicrystalline. Two ethynyl-terminated polyarylene ethers) weresynthesized by reacting hydroxy-terminated oligomers with4-ethynylbenzoyl chloride. Heat induced reaction of the acetylenicgroups provided materials with good solvent resistance. The chemistry,physical, and mechanical properties of the polymers are also disclosed.

S. J. Havens, "Ethynyl-Terminated Polyarylates: Synthesis andCharacterization," Journal of Polymer Science: Polymer ChemistryEdition, vol. 22, 3011-3025 (1984), the disclosure of which is totallyincorporated herein by reference, discloses hydroxy-terminatedpolyarylates with number average molecular weights of about 2500, 5000,7500, and 10,000 which were synthesized and converted to corresponding4-ethynylbenzoyloxy-terminated polyarylates by reaction with4-ethynylbenzoyl chloride. The terminal ethynyl groups were thermallyreacted to provide chain extension and crosslinking. The cured polymerexhibited higher glass transition temperatures and better solventresistance than a high molecular weight linear polyarylate. Solventresistance was further improved by curing2,2-bis(4-ethynylbenzoyloxy-4'-phenyl)propane, a coreactant, with theethynyl-terminated polymer at concentrations of about 10 percent byweight.

N. H. Hendricks and K. S. Y. Lau, "Flare, a Low Dielectric Constant,High T_(g), Thermally Stable Poly(arylene ether) Dielectric forMicroelectronic Circuit Interconnect Process Integration: Synthesis,Characterization, Thermomechanical Properties, and Thin-Film ProcessingStudies," Polymer Preprints, 37(1), 150 (1996), the disclosure of whichis totally incorporated herein by reference, discloses non-carbonylcontaining aromatic polyethers such as fluorinated poly(arylene ethers)based on decafluorobiphenyl as a class of intermetal dielectrics forapplications in sub-half micron multilevel interconnects.

J. J. Zupancic, D. C. Blazej, T. C. Baker, and E. A. Dinkel, "StyreneTerminated Resins as Interlevel Dielectrics for Multichip Models,"Polymer Preprints, 32, (2), 178 (1991), the disclosure of which istotally incorporated herein by reference, discloses vinylbenzyl ethersof polyphenols (styrene terminated resins) which were found to bephotochemically and thermally labile, generating highly crosslinkednetworks. The resins were found to yield no volatile by-products duringthe curing process and high glass transition, low dielectric constantcoatings. One of the resins was found to be spin coatable to varyingthickness coatings which could be photodefined, solvent developed, andthen hard baked to yield an interlevel dielectric.

Japanese Patent Kokai JP 04294148-A, the disclosure of which is totallyincorporated herein by reference, discloses a liquid injecting recordinghead containing the cured matter of a photopolymerizable compositioncomprising (1) a graft polymer comprising (A) alkyl methacrylate,acrylonitrile, and/or styrene as the trunk chain and an --OHgroup-containing acryl monomer, (B) amino or alkylamino group-containingacryl monomer, (C) carboxyl group-containing acryl or vinyl monomers,(D) N-vinyl pyrrolidone, vinyl pyridine or its derivatives, and/or (F)an acrylamide as the side chain; (2) a linear polymer containingconstitutional units derived from methyl methacrylate, ethylmethacrylate, isobutyl methacrylate, t-butyl methacrylate, benzylmethacrylate, acrylonitrile, isobornyl methacrylate, tricyclodecaneacrylate, tricyclodecane oxyethyl methacrylate, styrene,dimethylaminoethyl methacrylate, and/or cyclohexyl methacrylate, andconstitutional unit derived from the above compounds (A), (B), (C), (D),(E), or (F) above; (3) an ethylenic unsaturated bond containing monomer;and (4) a photopolymerization initiator which contains (a) an organicperoxide, s-triazine derivative, benzophenone or its derivatives,quinones, N-phenylglycine, and/or alkylarylketones as a radicalgenerator and (b) coumarin dyes, ketocoumarin dyes, cyanine dyes,merocyanine dyes, and/or xanthene dyes as a sensitizer.

"Functional Polymers and Sequential Copolymers by Phase TransferCatalysis, 2a: Synthesis and Characterization of Aromatic Poly(ethersulfone)s Containing Vinylbenzyl and Ethynylbenzyl Chain Ends," V.Percec and B. C. Auman, Makromol. Chem., 185, 1867-1880 (1984), thedisclosure of which is totally incorporated herein by reference,discloses a method for the synthesis of α,ω-bis(vinylbenzyl) aromaticpoly(ether sulfone)s and their transformation intoα,ω-bis(ethynylbenzyl) aromatic poly(ether sulfone)s. The method entailsa fast and quantitative Williamson etherification of theα,ω-bis(hydroxyphenyl) polysulfone with a mixture of p- andm-chloromethylstyrenes in the presence of tetrabutylammonium hydrogensulfate as phase transfer catalyst, a subsequent bromination, and then adehydrobromination with potassium tert-butoxide. The DSC study of thethermal curing of the α,ω-bis(vinylbenzyl) aromatic poly(ether sulfone)sand α,ω-bis(ethynylbenzyl) aromatic poly(ether sulfone)s demonstrateshigh thermal reactivity for the styrene-terminated oligomers.

"Functional Polymers and Sequential Copolymers by Phase TransferCatalysis, 3a: Synthesis and Characterization of Aromatic Poly(ethersulfone)s and Poly(oxy-2,6-dimethyl- 1,4-phenylene) Containing PendentVinyl Groups," V. Percec and B. C. Auman, Makromol. Chem., 185,2319-2336 (1984), the disclosure of which is totally incorporated hereinby reference, discloses a method for the syntheses of α,ω-benzylaromatic poly(ether sulfone)s (PSU) andpoly(oxy-2,6-dimethyl-1,4-phenylene) (POP) containing pendant vinylgroups. The first step of the synthetic procedure entails thechloromethylation of PSU and POP to provide polymers with chloromethylgroups. POP, containing bromomethyl groups, was obtained by radicalbromination of the methyl groups. Both chloromethylated andbromomethylated starting materials were transformed into theirphosphonium salts, and then subjected to a phase transfer catalyzedWittig reaction to provide polymers with pendant vinyl groups. A PSUwith pendant ethynyl groups was prepared by bromination of the PSUcontaining vinyl groups, followed by a phase transfer catalyzeddehydrobromination. DSC of the thermal curing of the polymers containingpendant vinyl and ethynyl groups showed that the curing reaction is muchfaster for the polymers containing vinyl groups. The resulting networkpolymers are flexible when the starting polymer contains vinyl groups,and very rigid when the starting polymer contains ethynyl groups.

"Functional Polymers and Sequential Copolymers by Phase TransferCatalysis," V. Percec and P. L. Rinaldi, Polymer Bulletin, 10, 223(1983), the disclosure of which is totally incorporated herein byreference, discloses the preparation of p- andm-hydroxymethylphenylacetylenes by a two step sequence starting from acommercial mixture of p- and m-chloromethylstyrene, i.e., by thebromination of the vinylic monomer mixture followed by separation of m-and p-brominated derivatives by fractional crystallization, andsimultaneous dehydrobromination and nucleophilic substitution of the--Cl with --OH.

U.S. Pat. No. 4,110,279 (Nelson et al.), the disclosure of which istotally incorporated herein by reference, discloses a polymer derived byheating in the presence of an acid catalyst at between about 65° C. andabout 250° C.: I. a reaction product, a cogeneric mixture of alkoxyfunctional compounds, having average equivalent weights in the range offrom about 220 to about 1200, obtained by heating in the presence of astrong acid at about 50° C. to about 250° C.: (A) a diary compoundselected from naphthalene, diphenyl oxide, diphenyl sulfide, theiralkylated or halogenated derivatives, or mixtures thereof, (B)formaldehyde or formaldehyde yielding derivative, (C) water, and (D) ahydroxy aliphatic hydrocarbon compound having at least one free hydroxylgroup and from 1 to 4 carbon atoms, which mixture contains up to 50percent unreacted (A); with II. at least one monomeric phenolic reactantselected from the group ##STR10## wherein R is selected from the groupconsisting of hydrogen, alkyl radical of 1 to 20 carbon atoms, arylradical of 6 to 20 carbon atoms, wherein R₁ represents hydrogen, alkyl,or aryl, m represents an integer from 1 to 3, o represents an integerfrom 1 to 5, p represents an integer from 0 to 3, X represents oxygen,sulfur, or alkylidene, and q represents an integer from 0 to 1; and III.optionally an aldehyde or aldehyde-yielding derivative or ketone, forfrom several minutes to several hours. The polymeric materials areliquids or low melting solids which are capable of further modificationto thermoset resins. These polymers are capable of being thermoset byheating at a temperature of from about 130° C. to about 260° C. for fromseveral minutes to several hours in the presence of aformaldehyde-yielding compound. These polymers are also capable offurther modification by reacting under basic conditions withformaldehyde with or without a phenolic compound. The polymers, bothbase catalyzed resoles and acid catalyzed novolacs, are useful aslaminating, molding, film-forming, and adhesive materials. The polymers,both resoles and novolacs, can be epoxidized as well as reacted with adrying oil to produce a varnish resin.

U.S. Pat. No. 3,367,914 (Herbert), the disclosure of which is totallyincorporated herein by reference, discloses thermosetting resinousmaterials having melting points in the range of from 150° C. to 350° C.which are made heating at a temperature of from -10° C. to 100° C. for 5to 30 minutes an aldehyde such as formaldehyde or acetaldehyde with amixture of poly(aminomethyl) diphenyl ethers having an average of fromabout 1.5 to 4.0 aminomethyl groups. After the resins are cured underpressure at or above the melting point, they form adherent tough filmson metal substrates and thus are useful as wire coatings for electricalmagnet wire for high temperature service at 180° C. or higher.

J. S. Amato, S. Karady, M. Sletzinger, and L. M. Weinstock, "A NewPreparation of Chloromethyl Methyl Ether Free of Bis(chloromethyl)Ether," Synthesis, 970 (1979), the disclosure of which is totallyincorporated herein by reference, discloses the synthesis ofchloromethyl methyl ether by the addition of acetyl chloride to a slightexcess of anhydrous dimethoxymethane containing a catalytic amount ofmethanol at room temperature. The methanol triggers a series ofreactions commencing with formation of hydrogen chloride and thereaction of hydrogen chloride with dimethoxymethane to form chloromethylmethyl ether and methanol in an equilibrium process. After 36 hours, anear-quantitative conversion to an equimolar mixture of chloromethylmethyl ether and methyl acetate is obtained.

A. McKillop, F. A. Madjdabadi, and D. A. Long, "A Simple and InexpensiveProcedure for Chloromethylation of Certain Aromatic Compounds,"Tetrahedron Lefters, Vol. 24, No. 18, pp. 1933-1936 (1983), thedisclosure of which is totally incorporated herein by reference,discloses the reaction of a range of aromatic compounds withmethoxyacetyl chloride and aluminum chloride in either nitromethane orcarbon disulfide to result in chloromethylation in good to excellentyield.

E. P. Tepenitsyna, M. 1. Farberov, and A. P. Ivanovskii, "Synthesis ofIntermediates for Production of Heat Resistant Polymers(Chloromethylation of Diphenyl Oxide)," Zhurnal Prikladnoi Khimii, Vol.40, No. 11, pp. 2540-2546 (1967), the disclosure of which is totallyincorporated herein by reference, discloses the chloromethylation ofdiphenyl oxide by (1) the action of paraformaldehyde solution in glacialacetic acid saturated with hydrogen chloride, and by (2) the action ofparaformaldehyde solution in concentrated hydrochloric acid.

U.S. Pat. No. 2,125,968 (Theimer), the disclosure of which is totallyincorporated herein by reference, discloses the manufacture of aromaticalcohols by the Friedel-Crafts reaction, in which an alkylene oxide iscondensed with a Friedel-Crafts reactant in the presence of an anhydrousmetal halide.

Copending application U.S. Ser. No. 08/705,914, filed Aug. 29, 1996,entitled "Thermal Ink Jet Printhead With Ink Resistant Heat SinkCoating," with the named inventors Ram S. Narang and Timothy J. Fuller,the disclosure of which is totally incorporated herein by reference,discloses a heat sink for a thermal ink jet printhead having improvedresistance to the corrosive effects of ink by coating the surface of theheat sink with an ink resistant film formed by electrophoreticallydepositing a polymeric material on the heat sink surface. In onedescribed embodiment, a thermal ink jet printer is formed by bondingtogether a channel plate and a heater plate. Resistors and electricalconnections are formed in the surface of the heater plate. The heaterplate is bonded to a heat sink comprising a zinc substrate having anelectrophoretically deposited polymeric film coating. The film coatingprovides resistance to the corrosion of higher pH inks. In anotherembodiment, the coating has conductive fillers dispersed therethrough toenhance the thermal conductivity of the heat sink. In one embodiment,the polymeric material is selected from the group consisting ofpolyethersulfones, polysulfones, polyamides, polyimides,polyamide-imides, epoxy resins, polyetherimides, polyarylene etherketones, chloromethylated polyarylene ether ketones, acryloylatedpolyarylene ether ketones, polystyrene and mixtures thereof.

Copending application U.S. Ser. No. 08/703,138, filed Aug. 29, 1996 U.S.Pat. No. 5,843,259, entitled "Method for Applying an Adhesive Layer to aSubstrate Surface," with the named inventors Ram S. Narang, Stephen F.Pond, and Timothy J. Fuller, the disclosure of which is totallyincorporated herein by reference, discloses a method for uniformlycoating portions of the surface of a substrate which is to be bonded toanother substrate. In a described embodiment, the two substrates arechannel plates and heater plates which, when bonded together, form athermal ink jet printhead. The adhesive layer is electrophoreticallydeposited over a conductive pattern which has been formed on the bindingsubstrate surface. The conductive pattern forms an electrode and isplaced in an electrophoretic bath comprising a colloidal emulsion of apreselected polymer adhesive. The other electrode is a metal containerin which the solution is placed or a conductive mesh placed within thecontainer. The electrodes are connected across a voltage source and afield is applied. The substrate is placed in contact with the solution,and a small current flow is carefully controlled to create an extremelyuniform thin deposition of charged adhesive micelles on the surface ofthe conductive pattern. The substrate is then removed and can be bondedto a second substrate and cured. In one embodiment, the polymer adhesiveis selected from the group consisting of polyamides, polyimides,polyamide-imides, epoxy resins, polyetherimides, polysulfones, polyethersulfones, polyarylene ether ketones, polystyrenes, chloromethylatedpolyarylene ether ketones, acryloylated plyarylene ether ketones, andmixtures thereof.

Copending application U.S. Ser. No. 08/697,750, filed , entitled"Electrophoretically Deposited Coating For the Front Face of an Ink JetPrinthead," with the named inventors Ram S. Narang, Stephen F. Pond, andTimothy J. Fuller, the disclosure of which is totally incorporatedherein by reference, discloses an electrophoretic deposition techniquefor improving the hydrophobicity of a metal surface, in one embodiment,the front face of a thermal ink jet printhead. For this example, a thinmetal layer is first deposited on the front face. The front face is thenlowered into a colloidal bath formed by a fluorocarbon-doped organicsystem dissolved in a solvent and then dispersed in a non-solvent. Anelectric field is created and a small amount of current through the bathcauses negatively charged particles to be deposited on the surface ofthe metal coating. By controlling the deposition time and currentstrength, a very uniform coating of the fluorocarbon compound is formedon the metal coating. The electrophoretic coating process is conductedat room temperature and enables a precisely controlled deposition whichis limited only to the front face without intrusion into the front faceorifices. In one embodiment, the organic compound is selected from thegroup consisting of polyimides, polyamides, polyamide-imides,polysulfones, polyarylene ether ketones, polyethersulfones,polytetrafluoroethylenes, polyvinylidene fluorides,polyhexafluoro-propylenes, epoxies, polypentafluorostyrenes,polystyrenes, copolymers thereof, terpolymers thereof, and mixturesthereof.

Copending application U.S. Ser. No. 08/705,916, filed Aug. 29, 1996,entitled "Stabilized Graphite Substrates," with the named inventors GaryA. Kneezel, Ram S. Narang, Timothy J. Fuller, and Peter J. John, thedisclosure of which is totally incorporated herein by reference,discloses an apparatus which comprises at least one semiconductor chipmounted on a substrate, said substrate comprising a graphite memberhaving electrophoretically deposited thereon a coating of a polymericmaterial. In one embodiment, the semiconductor chips are thermal ink jetprinthead subunits. In one embodiment, the polymeric material is of thegeneral formula ##STR11## wherein x is an integer of 0 or 1, A is one ofseveral specified groups, such as ##STR12## B is one of severalspecified groups, such as ##STR13## or mixtures thereof, and n is aninteger representing the number of repeating monomer units.

Copending application U.S. Ser. No. 08/705,375, filed Aug. 29, 1996,entitled "Improved Curable Compositions," with the named inventorsTimothy J. Fuller, Ram S. Narang, Thomas W. Smith, David J. Luca, andRalph A. Mosher, the disclosure of which is totally incorporated hereinby reference, discloses an improved composition comprising aphotopatternable polymer containing at least some monomer repeat unitswith photosensitivity-imparting substituents, said photopatternablepolymer being of the general formula ##STR14## wherein x is an integerof 0 or 1, A is one of several specified groups, such as ##STR15## B isone of several specified groups, such as ##STR16## or mixtures thereof,and n is an integer representing the number of repeating monomer units.Also disclosed is a process for preparing a thermal ink jet printheadwith the aforementioned polymer and a thermal ink jet printheadcontaining therein a layer of a crosslinked or chain extended polymer ofthe above formula.

Copending application U.S. Ser. No. 08/705,365, filed Aug. 29, 1996,entitled "Hydroxyalkylated High Performance Curable Polymers," with thenamed inventors Ram S. Narang and Timothy J. Fuller, the disclosure ofwhich is totally incorporated herein by reference, discloses acomposition which comprises (a) a polymer containing at least somemonomer repeat units with photosensitivity-imparting substituents whichenable crosslinking or chain extension of the polymer upon exposure toactinic radiation, said polymer being of the formula ##STR17## wherein xis an integer of 0 or 1, A is one of several specified groups, such as##STR18## B is one of several specified groups, such as ##STR19## ormixtures thereof, and n is an integer representing the number ofrepeating monomer units, wherein said photosensitivity-impartingsubstituents are hydroxyalkyl groups; (b) at least one member selectedfrom the group consisting of photoinitiators and sensitizers; and (c) anoptional solvent. Also disclosed are processes for preparing the abovepolymers and methods of preparing thermal ink jet printheads containingthe above polymers.

Copending application U.S. Ser. No. )8/705,488, filed Aug. 29, 1996,entitled "Improved High Performance Polymer Compositions," with thenamed inventors Thomas W. Smith, Timothy J. Fuller, Ram S. Narang, andDavid J. Luca, the disclosure of which is totally incorporated herein byreference, discloses a composition comprising a polymer with a weightaverage molecular weight of from about 1,000 to about 65,000, saidpolymer containing at least some monomer repeat units with a first,photosensitivity-imparting substituent which enables crosslinking orchain extension of the polymer upon exposure to actinic radiation, saidpolymer also containing a second, thermal sensitivity-impartingsubstituent which enables further polymerization of the polymer uponexposure to temperatures of about 140° C. and higher, wherein the firstsubstituent is not the same as the second substituent, said polymerbeing selected from the group consisting of polysulfones,polyphenylenes, polyether sulfones, polyimides, polyamide imides,polyarylene ethers, polyphenylene sulfides, polyarylene ether ketones,phenoxy resins, polycorbonates, polyether imides, polyquinoxalines,polyquinolines, polybenzimidazoles, polybenzoxazoles,polybenzothiazoles, polyoxadiazoles, copolymers thereof, and mixturesthereof.

Copending application U.S. Ser. No. 08/697,761, filed Aug. 29, 1996,entitled "Process for Direct Substitution of High Performance Polymerswith Unsaturated Ester Groups," with the named inventors Timothy J.Fuller, Ram S. Narang, Thomas W. Smith, David J. Luca, and Raymond K.Crandall, the disclosure of which is totally incorporated herein byreference, discloses a process which comprises reacting a polymer of thegeneral formula ##STR20## wherein x is an integer of 0 or 1, A is one ofseveral specified groups, such as ##STR21## B is one of severalspecified groups, such as ##STR22## or mixtures thereof, and n is aninteger representing the number of repeating monomer units, with (i) aformaldehyde source, and (ii) an unsaturated acid in the presence of anacid catalyst, thereby forming a curable polymer with unsaturated estergroups. Also disclosed is a process for preparing an ink jet printheadwith the above polymer.

Copending application U.S. Ser. No. 08/705,463, filed Aug. 29, 1996 U.S.Pat. No. 7,739,254, entitled "Process for Haloalkylation of HighPerformance Polymers," with the named inventors Timothy J. Fuller, RamS. Narang, Thomas W. Smith, David J. Luca, and Raymond K. Crandall, thedisclosure of which is totally incorporated herein by reference,discloses a process which comprises reacting a polymer of the generalformula ##STR23## wherein x is an integer of 0 or 1, A is one of severalspecified groups, such as ##STR24## B is one of several specifiedgroups, such as ##STR25## or mixtures thereof, and n is an integerrepresenting the number of repeating monomer units, with an acetylhalide and dimethoxymethane in the presence of a halogen-containingLewis acid catalyst and methanol, thereby forming a haloalkylatedpolymer. In a specific embodiment, the haloalkylated polymer is thenreacted further to replace at least some of the haloalkyl groups withphotosensitivity-imparting groups. Also disclosed is a process forpreparing a thermal ink jet printhead with the aforementioned polymer.

Copending application U.S. Ser. No. 08/705,479, filed Aug. 29, 1996 U.S.Pat. No. 5,761,809, entitled "Processes for Substituting HaloalkylatedPolymers With Unsaturated Ester, Ether, and AlkylcarboxymethyleneGroups," with the named inventors Timothy J. Fuller, Ram S. Narang,Thomas W. Smith, David J. Luca, and Raymond K. Crandall, the disclosureof which is totally incorporated herein by reference, discloses aprocess which comprises reacting a haloalkylated aromatic polymer with amaterial selected from the group consisting of unsaturated ester salts,alkoxide salts, alkylcarboxylate salts, and mixtures thereof, therebyforming a curable polymer having functional groups corresponding to theselected salt. Another embodiment of the invention is directed to aprocess for preparing an ink jet printhead with the curable polymer thusprepared.

Copending application U.S. Ser. No. 08/705,376, filed Aug. 29, 1996,entitled "Blends Containing Curable Polymers," with the named inventorsRam S. Narang and Timothy J. Fuller, the disclosure of which is totallyincorporated herein by reference, discloses a composition whichcomprises a mixture of (A) a first component comprising a polymer, atleast some of the monomer repeat units of which have at least onephotosensitivity-imparting group thereon, said polymer having a firstdegree of photosensitivity-imparting group substitution measured inmilliequivalents of photosensitivity-imparting group per gram and beingof the general formula ##STR26## wherein x is an integer of 0 or 1, A isone of several specified groups, such as ##STR27## B is one of severalspecified groups, such as ##STR28## or mixtures thereof, and n is aninteger representing the number of repeating monomer units, and (B) asecond component which comprises either (1) a polymer having a seconddegree of photosensitivity-imparting group substitution measured inmilliequivalents of photosensitivity-imparting group per gram lower thanthe first degree of photosensitivity-imparting group substitution,wherein said second degree of photosensitivity-imparting groupsubstitution may be zero, wherein the mixture of the first component andthe second component has a third degree of photosensitivity-impartinggroup substitution measured in milliequivalents ofphotosensitivity-imparting group per gram which is lower than the firstdegree of photosensitivity-imparting group substitution and higher thanthe second degree of photosensitivity-imparting group substitution, or(2) a reactive diluent having at least one photosensitivity-impartinggroup per molecule and having a fourth degree ofphotosensitivity-imparting group substitution measured inmilliequivalents of photosensitivity-imparting group per gram, whereinthe mixture of the first component and the second component has a fifthdegree of photosensitivity-imparting group substitution measured inmilliequivalents of photosensitivity-imparting group per gram which ishigher than the first degree of photosensitivity-imparting groupsubstitution and lower than the fourth degree ofphotosensitivity-imparting group substitution; wherein the weightaverage molecular weight of the mixture is from about 10,000 to about50,000; and wherein the third or fifth degree ofphotosensitivity-imparting group substitution is from about 0.25 toabout 2 milliequivalents of photosensitivity-imparting groups per gramof mixture.

Also disclosed is a process for preparing a thermal ink jet printheadwith the aforementioned composition.

Copending application U.S. Ser. No. 08/705,372, filed Aug. 29, 1996,entitled "High Performance Curable Polymers and Processes for thePreparation Thereof," with the named inventors Ram S. Narang and TimothyJ. Fuller, the disclosure of which is totally incorporated herein byreference, discloses a composition which comprises a polymer containingat least some monomer repeat units with photosensitivity-impartingsubstituents which enable crosslinking or chain extension of the polymerupon exposure to actinic radiation, said polymer being of the formula##STR29## wherein x is an integer of 0 or 1, A is one of severalspecified groups, such as ##STR30## B is one of several specifiedgroups, such as ##STR31## or mixtures thereof, and n is an integerrepresenting the number of repeating monomer units, wherein saidphotosensitivity-imparting substituents are allyl ether groups, epoxygroups, or mixtures thereof. Also disclosed are a process for preparinga thermal ink jet printhead containing the aforementioned polymers andprocesses for preparing the aforementioned polymers.

Copending application U.S. Ser. No. )8/697,760, filed Aug. 29, 1996,entitled "Aqueous Developable High Performance Curable Polymers," withthe named inventors Ram S. Narang and Timothy J. Fuller, the disclosureof which is totally incorporated herein by reference, discloses acomposition which comprises a polymer containing at least some monomerrepeat units with water-solubility-imparting substituents and at leastsome monomer repeat units with photosensitivity-imparting substituentswhich enable crosslinking or chain extension of the polymer uponexposure to actinic radiation, said polymer being of the formula##STR32## wherein x is an integer of 0 or 1, A is one of severalspecified groups, such as ##STR33## B is one of several specifiedgroups, such as ##STR34## or mixtures thereof, and n is an integerrepresenting the number of repeating monomer units. In one embodiment, asingle functional group imparts both photosensitivity and watersolubility to the polymer. In another embodiment, a first functionalgroup imparts photosensitivity to the polymer and a second functionalgroup imparts water solubility to the polymer. Also disclosed is aprocess for preparing a thermal ink jet printhead with theaforementioned polymers.

While known compositions and processes are suitable for their intendedpurposes, a need remains for improved materials suitable formicroelectronics applications. A need also remains for improved ink jetprintheads. Further, there is a need for photopatternable polymericmaterials which are heat stable, electrically insulating, andmechanically robust. Additionally, there is a need for photopatternablepolymeric materials which are chemically inert with respect to thematerials that might be employed in ink jet ink compositions. There isalso a need for photopatternable polymeric materials which exhibit lowshrinkage during post-cure steps in microelectronic device fabricationprocesses. In addition, a need remains for photopatternable polymericmaterials which exhibit a relatively long shelf life. Further, there isa need for photopatternable polymeric materials which are resistant toattack from high pH inks. Additionally, a need remains forphotopatternable polymeric materials which, in the cured form, exhibitgood solvent resistance. There is also a need for photopatternablepolymeric materials which, when applied to microelectronic devices byspin casting techniques and cured, exhibit reduced edge bead and noapparent lips and dips. In addition, a need remains for photopatternablepolymeric materials which allow the production of high aspect ratiofeatures at very high resolutions. Further, a need remains forphotopatternable polymeric materials which are suitable for use inprocesses using e-beam and deep UV radiation for imaging. In addition,there remains a need for photopatternable polymeric materials which haverelatively low dielectric constants. Further, there is a need forphotopatternable polymeric materials which exhibit reduced watersorption. Additionally, a need remains for photopatternable polymericmaterials which exhibit improved hydrolytic stability, especially uponexposure to alkaline solutions. A need also remains for photopatternablepolymeric materials which are stable at high temperatures, typicallygreater than about 150° C. There is also a need for photopatternablepolymeric materials which either have high glass transition temperaturesor are sufficiently crosslinked that there are no low temperature phasetransitions subsequent to photoexposure. Further, a need remains forphotopatternable polymeric materials with low coefficients of thermalexpansion. There is a need for polymers which are thermally stable,patternable as thick films of about 30 microns or more, exhibit lowT_(g) prior to photoexposure, have low dielectric constants, are low inwater absorption, have low coefficients of expansion, have desirablemechanical and adhesive characteristics, and are generally desirable forinterlayer dielectric applications, including those at hightemperatures, which are also photopatternable. There is also a need forphotoresist compositions with good to excellent processingcharacteristics.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide polymeric materialswith the above noted advantages.

It is another object of the present invention to provide improvedmaterials suitable for microelectronics applications.

It is yet another object of the present invention to provide improvedink jet printheads.

It is still another object of the present invention to providephotopatternable polymeric materials which are heat stable, electricallyinsulating, and mechanically robust.

Another object of the present invention is to provide photopatternablepolymeric materials which are chemically inert with respect to thematerials that might be employed in ink jet ink compositions.

Yet another object of the present invention is to providephotopatternable polymeric materials which exhibit low shrinkage duringpost-cure steps in microelectronic device fabrication processes.

Still another object of the present invention is to providephotopatternable polymeric materials which exhibit a relatively longshelf life.

It is another object of the present invention to providephotopatternable polymeric materials which are resistant to attack fromhigh pH inks.

It is yet another object of the present invention to providephotopatternable polymeric materials which, in the cured form, exhibitgood solvent resistance.

It is still another object of the present invention to providephotopatternable polymeric materials which, when applied tomicroelectronic devices by spin casting techniques and cured, exhibitreduced edge bead and no apparent lips and dips.

Another object of the present invention is to provide photopatternablepolymeric materials which allow the production of high aspect ratiofeatures at very high resolutions.

Yet another object of the present invention is to providephotopatternable polymeric materials which are suitable for use inprocesses using e-beam and deep UV radiation for imaging.

Still another object of the present invention is to providephotopatternable polymeric materials which have relatively lowdielectric constants.

It is another object of the present invention to providephotopatternable polymeric materials which exhibit reduced watersorption.

It is yet another object of the present invention to providephotopatternable polymeric materials which exhibit improved hydrolyticstability, especially upon exposure to alkaline solutions.

It is still another object of the present invention to providephotopatternable polymeric materials which are stable at hightemperatures, typically greater than about 150° C.

Another object of the present invention is to provide photopatternablepolymeric materials which either have high glass transition temperaturesor are sufficiently crosslinked that there are no low temperature phasetransitions subsequent to photoexposure.

Yet another object of the present invention is to providephotopatternable polymeric materials with low coefficients of thermalexpansion.

Still another object of the present invention is to provide polymerswhich are thermally stable, patternable as thick films of about 30microns or more, exhibit low T_(g) prior to photoexposure, have lowdielectric constants, are low in water absorption, have low coefficientsof expansion, have desirable mechanical and adhesive characteristics,and are generally desirable for interlayer dielectric applications,including those at high temperatures, which are also photopatternable.

It is another object of the present invention to provide photoresistcompositions with good to excellent processing characteristics.

These and other objects of the present invention (or specificembodiments thereof) can be achieved by providing a process whichcomprises the steps of (a) providing a polymer containing at least somemonomer repeat units with halomethyl group substituents which enablecrosslinking or chain extension of the polymer upon exposure to aradiation source which is electron beam radiation, x-ray radiation, ordeep ultraviolet radiation, said polymer being of the formula ##STR35##wherein x is an integer of 0 or 1, A is ##STR36## or mixtures thereof, Bis ##STR37## wherein v is an integer of from 1 to about 20, ##STR38##wherein z is an integer of from 2 to about 20, ##STR39## wherein u is aninteger of from 1 to about 20, ##STR40## wherein w is on integer of from1 to about 20, ##STR41## or mixtures thereof, and n is an integerrepresenting the number of repeating monomer units, and (b) causing thepolymer to become crosslinked or chain extended through thephotosensitivity-imparting groups. Another embodiment of the presentinvention is directed to a process which comprises the steps of:

(a) depositing a layer comprising a polymer of the above formula onto alower substrate in which one surface thereof has an array of heatingelements and addressing electrodes having terminal ends formed thereon,said polymer being deposited onto the surface having the heatingelements and addressing electrodes thereon;

(b) exposing the layer to a radiation source which is electron beamradiation, x-ray radiation, or deep ultraviolet radiation in animagewise pattern such that the polymer in exposed areas becomescrosslinked or chain extended and the polymer in unexposed areas doesnot become crosslinked or chain extended, wherein the unexposed areascorrespond to areas of the lower substrate having thereon the heatingelements and the terminal ends of the addressing electrodes;

(c) removing the polymer from the unexposed areas, thereby formingrecesses in the layer, said recesses exposing the heating elements andthe terminal ends of the addressing electrodes;

(d) providing an upper substrate with a set of parallel grooves forsubsequent use as ink channels and a recess for subsequent use as amanifold, the grooves being open at one end for serving as dropletemitting nozzles; and

(e) aligning, mating, and bonding the upper and lower substratestogether to form a printhead with the grooves in the upper substratebeing aligned with the heating elements in the lower substrate to formdroplet emitting nozzles, thereby forming a thermal ink jet printhead.Yet another embodiment of the present invention is directed to specificpolymeric compositions within the above formula.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an enlarged schematic isometric view of an example of aprinthead mounted on a daughter board showing the droplet emittingnozzles.

FIG. 2 is an enlarged cross-sectional view of FIG. 1 as viewed along theline 2--2 thereof and showing the electrode passivation and ink flowpath between the manifold and the ink channels.

FIG. 3 is an enlarged cross-sectional view of an alternate embodiment ofthe printhead in FIG. 1 as viewed along the line 2-2 thereof.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed to halomethylated curable highperformance polymer compositions. High performance polymers typicallyare moldable at temperatures above those at which their use is intended,and are useful for high temperature structural applications. While mosthigh performance polymers are thermoplastic, some, such as phenolics,tend to be thermosetting. The halomethylated polymers are prepared frompolymers of the following formula: ##STR42## wherein x is an integer of0 or 1, A is ##STR43## or mixtures thereof, B is ##STR44## wherein v isan integer of from 1 to about 20, and preferably from 1 to about 10,##STR45## wherein z is an integer of from 2 to about 20, and preferablyfrom 2 to about 10, ##STR46## wherein u is an integer of from 1 to about20, and preferably from 1 to about 10, ##STR47## wherein w is an integerof from 1 to about 20, and preferably from 1 to about 10, ##STR48##other similar bisphenol derivatives, or mixtures thereof, and n is aninteger representing the number of repeating monomer units. The value ofn is such that the weight average molecular weight of the materialtypically is from about 1,000 to about 100,000, preferably from about1,000 to about 65,000, more preferably from about 1,000 to about 40,000,and even more preferably from about 3,000 to about 25,000, although theweight average molecular weight can be outside these ranges. Preferably,n is an integer of from about 2 to about 70, more preferably from about5 to about 70, and even more preferably from about 8 to about 50,although the value of n can be outside these ranges. The phenyl groupsand the A and/or B groups may also be substituted, although the presenceof two or more substituents on the B group ortho to the oxygen groupscan render substitution difficult. Substituents can be present on thepolymer either prior to or subsequent to the placement of halomethylgroups thereon. Substituents can also be placed on the polymer duringthe process of placement of halomethyl groups thereon. Examples ofsuitable substituents include (but are not limited to) alkyl groups,including saturated, unsaturated, and cyclic alkyl groups, preferablywith from 1 to about 6 carbon atoms, substituted alkyl groups, includingsaturated, unsaturated, and cyclic substituted alkyl groups, preferablywith from 1 to about 6 carbon atoms, aryl groups, preferably with from 6to about 24 carbon atoms, substituted aryl groups, preferably with from6 to about 24 carbon atoms, arylalkyl groups, preferably with from 7 toabout 30 carbon atoms, substituted arylalkyl groups, preferably withfrom 7 to about 30 carbon atoms, alkoxy groups, preferably with from 1to about 6 carbon atoms, substituted alkoxy groups, preferably with from1 to about 6 carbon atoms, aryloxy groups, preferably with from 6 toabout 24 carbon atoms, substituted aryloxy groups, preferably with from6 to about 24 carbon atoms, arylalkyloxy groups, preferably with from 7to about 30 carbon atoms, substituted arylalkyloxy groups, preferablywith from 7 to about 30 carbon atoms, hydroxy groups, amine groups,imine groups, ammonium groups, pyridine groups, pyridinium groups, ethergroups, ester groups, amide groups, carbonyl groups, thiocarbonylgroups, sulfate groups, sulfonate groups, sulfide groups, sulfoxidegroups, phosphine groups, phosphonium groups, phosphate groups, mercaptogroups, nitroso groups, sulfone groups, acyl groups, acid anhydridegroups, azide groups, and the like, wherein the substituents on thesubstituted alkyl groups, substituted aryl groups, substituted arylalkylgroups, substituted alkoxy groups, substituted aryloxy groups, andsubstituted arylalkyloxy groups can be (but are not limited to) hydroxygroups, amine groups, imine groups, ammonium groups, pyridine groups,pyridinium groups, ether groups, aldehyde groups, ketone groups, estergroups, amide groups, carboxylic acid groups, carbonyl groups,thiocarbonyl groups, sulfate groups, sulfonate groups, sulfide groups,sulfoxide groups, phosphine groups, phosphonium groups, phosphategroups, cyano groups, nitrile groups, mercapto groups, nitroso groups,halogen atoms, nitro groups, sulfone groups, acyl groups, acid anhydridegroups, azide groups, mixtures thereof, and the like, wherein two ormore substituents can be joined together to form a ring. Processes forthe preparation of these materials are known, and disclosed in, forexample, P. M. Hergenrother, J. Macromol. Sci. Rev. Macromol. Chem., C19(1), 1-34 (1980); P. M. Hergenrother, B. J. Jensen, and S. J. Havens,Polymer, 29, 358 (1988); B. J. Jensen and P. M. Hergenrother, "HighPerformance Polymers," Vol. 1, No. 1) page 31 (1989), "Effect ofMolecular Weight on Poly(arylene ether ketone) Properties"; V. Percecand B. C. Auman, Makromol. Chem. 185, 2319 (1984); "High MolecularWeight Polymers by Nickel Coupling of Aryl Polychlorides," I. Colon, G.T. Kwaiatkowski, J. of Polymer Science, Part A, Polymer Chemistry, 28,367 (1990); M. Ueda and T. Ito, Polymer J., 23 (4), 297 (1991);"Ethynyl-Terminated Polyarylates: Synthesis and Characterization," S. J.Havens and P. M. Hergenrother, J. of Polymer Science: Polymer ChemistryEdition, 22, 3011 (1984); "Ethynyl-Terminated Polysulfones: Synthesisand Characterization," P. M. Hergenrother, J. of Polymer Science:Polymer Chemistry Edition, 20, 3131 (1982); K. E. Dukes, M. D. Forbes,A. S. Jeevarajan, A. M. Belu, J. M. DeDimone, R. W. Linton, and V. V.Sheares, Macromolecules, 29, 3081 (1996); G. Houghom, G. Tesoro, and J.Shaw, Polym. Mater. Sci. Eng., 61, 369 (1989); V. Percec and B. C.Auman, Makromol. Chem, 185, 617 (1984); "Synthesis and characterizationof New Fluorescent Poly(arylene ethers)," S. Matsuo, N. Yakoh, S. Chino,M. Mitani, and S. Tagami, Journal of Polymer Science: Part A: PolymerChemistry, 32, 1071 (1994); "Synthesis of a Novel Naphthalene-BasedPoly(arylene ether ketone) with High Solubility and Thermal Stability,"Mami Ohno, Toshikazu Takata, and Takeshi Endo, Macromolecules, 27, 3447(1994); "Synthesis and Characterization of New Aromatic Poly(etherketones)," F. W. Mercer, M. T. Mckenzie, G. Merlino, and M. M. Fone, J.of Applied Polymer Science, 56, 1397 (1995); H. C. Zhang, T. L. Chen, Y.G. Yuan, Chinese Patent CN 85108751 (1991); "Static and laser lightscattering study of novel thermoplastics. 1. Phenolphthalein poly(arylether ketone)," C. Wu, S. Bo, M. Siddiq, G. Yang and T. Chen,Macromolecules, 29, 2989 (1996); "Synthesis of t-Butyl-SubstitutedPoly(ether ketone) by Nickel-Catalyzed Coupling Polymerization ofAromatic Dichloride", M. Ueda, Y. Seino, Y. Haneda, M. Yoneda, and J.-I.Sugiyama, Journal of Polymer Science: Part A: Polymer Chemistry, 32, 675(1994); "Reaction Mechanisms: Comb-Like Polymers and Graft Copolymersfrom Macromers 2. Synthesis, Characterzation and Homopolymerization of aStyrene Macromer of Poly(2,6-dimethyl-1,4-phenylene Oxide)," V. Percec,P. L. Rinaldi, and B. C. Auman, Polymer Bulletin, 10, 397 (1983);Handbook of Polymer Synthesis Part A, Hans R. Kricheldorf, ed., MarcelDekker, Inc., New York-Basel-Hong Kong (1992); and "Introduction ofCarboxyl Groups into Crosslinked Polystyrene," C. R. Harrison, P. Hodge,J. Kemp, and G. M. Perry, Die Makromolekulare Chemie, 176, 267 (1975),the disclosures of each of which are totally incorporated herein byreference. Further background on high performance polymers is disclosedin, for example, U.S. Pat. No. 2,822,351; U.S. Pat. No. 3,065,205;British Patent 1,060,546; British Patent 971,227; British Patent1,078,234; U.S. Pat. No. 4,175,175; N. Yoda and H. Hiramoto, J.Macromol. Sci.-Chem., A21(13 &14) pp. 1641 (1984) (Toray Industries,Inc., Otsu, Japan; B. Sillion and L. Verdet, "Polyimides and otherHigh-Temperature polymers", edited by M. J. M. Abadie and B. Sillion,Elsevier Science Publishers B.V. (Amsterdam 1991); "Polyimides withAlicyclic Diamines. II. Hydrogen Abstraction and PhotocrosslinkingReactions of Benzophenone Type Polyimides," Q. Jin, T. Yamashita, and K.Horie, J. of Polymer Science: Part A: Polymer Chemistry, 32, 503 (1994);Probimide™ 300, product bulletin, Ciba-Geigy Microelectronics Chemicals,"Photosensitive Polyimide System"; High Performance Polymers andComposites, J. I. Kroschwitz (ed.), John Wiley & Sons (New York 1991);and T. E. Atwood, D. A. Barr, T. A. King, B. Newton, and B. J. Rose,Polymer, 29, 358 (1988), the disclosures of each of which are totallyincorporated herein by reference. Further information on radiationcuring is disclosed in, for example, Radiation Curing: Science andTechnology, S. Peter Pappas, ed., Plenum Press (New York 1992), thedisclosure of which is totally incorporated herein by reference.

For applications wherein the photopatternable polymer is to be used as alayer in a thermal ink jet printhead, the polymer preferably has anumber average molecular weight of from about 3,000 to about 20,000Daltons, more preferably from about 3,000 to about 10,000 Daltons, andeven more preferably from about 3,500 to about 6,500 Daltons, althoughthe molecular weight can be outside this range.

The polymer material is halomethylated at one or more sites, as follows:##STR49## wherein X represents a halogen atom, such as fluorine,chlorine, bromine, iodine, or the like. Substitution is generallyrandom, although the substituent often indicates a preference for the Bgroup, and particularly for the sites ortho to oxygen on the B group,and any given monomer repeat unit may have no halomethyl substituents,one halomethyl substituent, or two or more halomethyl substituents. Mostcommonly, a particular monomer repeat unit will have no or onehalomethyl group per aromatic ring.

Halomethylation of the polymer can be carried out by any suitable ordesired process. For example, suitable halomethylation processes includereaction of the polymers with formaldehyde and hydrohalic acid,bishalomethyl ether, halomethyl methyl ether, octylhalomethyl ether, orthe like, generally in the presence of a Lewis acid catalyst.Bromination of a methyl group on the polymer can also be accomplishedwith elemental bromine via a free radical process initiated by, forexample, a peroxide initiator or light. Halogen atoms can be substitutedfor other halogens already on a halomethyl group by, for example,reaction with the appropriate hydrohalic acid or halide salt. Methodsfor the halomethylation of polymers are also disclosed in, for example,"Chloromethylation of Condensation Polymers Containing anoxy-1,4-phenylene Backbone," W. H. Daly et al., Polymer Preprints, Vol.20, No. 1, 835 (1979), the disclosure of which is totally incorporatedherein by reference.

The halomethylation of the polymer can be accomplished by reacting thepolymer with an acetyl halide and dimethoxymethane in the presence of ahalogen-containing Lewis acid catalyst such as those of the generalformula

    M.sup.n⊕ X.sub.

wherein n is an integer of 1, 2, 3, 4, or 5, M represents a boron atomor a metal atom, such as tin, aluminum, zinc, antimony, iron (III),gallium, indium, arsenic, mercury, copper, platinum, palladium, or thelike, and X represents a halogen atom, such as fluorine, chlorine,bromine, or iodine, with specific examples including SnCl₄, AlCl₃,ZnCl₂, AlBr₃, BF₃, SbF₅, Fel₃, GaBr₃, InCl₃, Asl₅, HgBr₂, CuCl, PdCl₂,PtBr₂, or the like. Methanol is added to generate hydrohalic acidcatalytically; the hydrohalic acid reacts with dimethoxymethane to formhalomethyl methyl ether. Care must be taken to avoid cross-linking ofthe halomethylated polymer. Typically, the reactants are present inrelative amounts by weight of about 35.3 parts acetyl halide, about 37parts dimethoxymethane, about 1.2 parts methanol, about 0.3 parts Lewisacid catalyst, about 446 parts 1,1,2,2-tetrachloroethane, and about 10to 20 parts polymer. 1,1,2,2-Tetrachlorethane is a suitable reactionsolvent. Dichloromethane is low boiling, and consequently the reactionis slow in this solvent unless suitable pressure equipment is used.

The general reaction scheme illustrated below for the chloromethylationreaction, is as follows: ##STR50## Substitution is generally random,although the substituent often indicates a preference for the B group,and a particular preference for the sites ortho to oxygen on the Bgroup, and any given monomer repeat unit may have no halomethylsubstituents, one halomethyl substituent, or two or more halomethylsubstituents. Most commonly, each aromatic ring will have either nohalomethyl groups or one halomethyl group.

Typical reaction temperatures are from about 60 to about 120° C., andpreferably from about 80 to about 110° C., although the temperature canbe outside these ranges. Typical reaction times are from about 1 toabout 10 hours, and preferably from about 2 to about 4 hours, althoughthe time can be outside these ranges. Longer reaction times generallyresult in higher degrees of halomethylation. Different degrees ofhalomethylation may be desirable for different applications. Too high adegree of halomethylation may lead to excessive sensitivity, resultingin crosslinking or chain extension of both exposed and unexposed polymermaterial when the material is exposed imagewise to activating radiation,whereas too low a degree of halomethylation may be undesirable becauseof resulting unnecessarily long exposure times or unnecessarily highexposure energies. For applications wherein the photopatternable polymeris to be used as a layer in a thermal ink jet printhead, the degree ofhalomethylation (i.e., the average number of halomethyl groups permonomer repeat unit) preferably is from about 0.5 to about 1.2, and morepreferably from about 0.65 to about 0.8, although the degree ofhalomethylation can be outside these ranges for ink jet printheadapplications. Optimum amounts of halomethylation are from about 0.8 toabout 1.3 milliequivalents of halomethyl group per gram of resin.

The resulting material is of the general formula ##STR51## wherein Xrepresents a halogen atom and a, b, c, and d are each integers of 0, 1,2, 3, or 4, provided that at least one of a, b, c, and d is equal to orgreater than 1 in at least some of the monomer repeat units of thepolymer, and n is an integer representing the number of repeatingmonomer units.

Other procedures for placing functional groups on aromatic polymers aredisclosed in, for example, W. H. Daly, S. Chotiwana, and R. Nielsen,Polymer Preprints, 20(1), 835 (1979); "Functional Polymers andSequential Copolymers by Phase Transfer Catalysis, 3. Synthesis AndCharacterization of Aromatic Poly(ether sulfone)s andPoly(oxy-2,6-dimethyl-1,4-phenylene) Containing Pendant Vinyl Groups,"V. Percec and B. C. Auman, Makromol. Chem., 185, 2319 (1984); F. Wangand J. Roovers, Journal of Polymer Science: Part A: Polymer Chemistry,32, 2413 (1994); "Details Concerning the Chloromethylation of SolubleHigh Molecular Weight Polystyrene Using Dimethoxymethane, ThionylChloride, And a Lewis Acid: A Full Analysis," M. E. Wright, E. G.Toplikar, and S. A. Svejda, Macromolecules, 24, 5879 (1991); "FunctionalPolymers and Sequential Copolymers by Phase Transfer Catalysts," V.Percec and P. L. Rinaldi, Polymer Bulletin, 10, 223 (1983); "Preparationof Polymer Resin and Inorganic Oxide Supported Peroxy-Acids and TheirUse in the Oxidation of Tetrahydrothiophene," J. A. Greig, R. D.Hancock, and D. C. Sherrington, Euopeon Polymer J., 16, 293 (1980);"Preparation of Poly(vinylbenzyltriphenylphosphonium Perbromide) and ItsApplication in the Bromination of Organic Compounds," A. Akelah, M.Hassanein, and F. Abdel-Galil, European Polymer J., 20 (3) 221 (1984);J. M. J. Frechet and K. K. Haque, Macromelcules, 8, 130 (1975); U.S.Pat. No. 3,914,194; U.S. Pat. No. 4,110,279; U.S. Pat. No. 3,367,914;"Synthesis of Intermediates for Production of Heat Resistant Polymers(Chloromethylation of Diphenyl oxide)," E. P. Tepenitsyna, M. I.Farberov, and A. P. Ivanovski, Zhurnal Prikladnoi Khimii, Vol. 40, No.11, 2540 (1967); U.S. Pat. No. 3,000,839; Chem Abst. 56, 590f (1962);U.S. Pat. No. 3,128,258; Chem Abstr. 61, 4560a (1964); J. D. Doedens andH. P. Cordts, Ind. Eng. Ch., 83, 59 (1961); British Pat. No. 863,702;and Chem Abstr 55, 18667b (1961); the disclosures of each of which aretotally incorporated herein by reference.

While not required, it may be advantageous with respect to the ultimateproperties of the photopatterned polymer if the polymer isfunctionalized with a second thermally polymerizable group, typically(although not necessarily) one which reacts at a temperature in excessof the glass transition temperature of the crosslinked or chain extendedphotopatternable polymer. The second polymerizable group can be eitherappended to the polymer chain or present as a terminal end group.

Examples of suitable thermal sensitivity imparting groups includeethynyl groups, such as those of the formula

    --(R)a--C.tbd.C--R.sup.1

wherein R is ##STR52## a is an integer of 0 or 1, and R' is a hydrogenatom or a phenyl group, ethylenic linkage-containing groups, such asallyl groups, including those of the formula ##STR53## wherein X and Yeach, independently of the other, are hydrogen atoms or halogen atoms,such as fluorine, chlorine, bromine, or iodine, vinyl groups, includingthose of the formula ##STR54## wherein R is an alkyl group, includingboth saturated, unsaturated, linear, branched, and cyclic alkyl groups,preferably with from 1 to about 30 carbon atoms, more preferably withfrom 1 to about 11 carbon atoms, even more preferably with from 1 toabout 5 carbon atoms, a substituted alkyl group, an aryl group,preferably with from 6 to about 24 carbon atoms, more preferably withfrom 6 to about 18 carbon atoms, a substituted aryl group, an arylalkylgroup, preferably with from 7 to about 30 carbon atoms, more preferablywith from 7 to about 19 carbon atoms, or a substituted arylalkyl group,wherein the substituents on the substituted alkyl groups, substitutedaryl groups, substituted arylalkyl groups, substituted alkoxy groups,substituted aryloxy groups, and substituted arylalkyloxy groups can be(but are not limited to) hydroxy groups, amine groups, imine groups,ammonium groups, pyridine groups, pyridinium groups, ether groups,aldehyde groups, ketone groups, ester groups, amide groups, carboxylicacid groups, carbonyl groups, thiocarbonyl groups, sulfate groups,sulfonate groups, sulfide groups, sulfoxide groups, phosphine groups,phosphonium groups, phosphate groups, cyano groups, nitrile groups,mercapto groups, nitroso groups, halogen atoms, nitro groups, sulfonegroups, acyl groups, acid anhydride groups, azide groups, mixturesthereof, and the like, wherein any two or more substituents can bejoined together to form a ring, vinyl ether groups, such as those of theformula ##STR55## epoxy groups, including those of the formula ##STR56##R is an alkyl group, including both saturated, unsaturated, linear,branched, and cyclic alkyl groups, preferably with from 1 to about 30carbon atoms, more preferably with from 1 to about 11 carbon atoms, evenmore preferably with from 1 to about 5 carbon atoms, a substituted alkylgroup, an aryl group, preferably with from 6 to about 24 carbon atoms,more preferably with from 6 to about 18 carbon atoms, a substituted arylgroup, an arylalkyl group, preferably with from 7 to about 30 carbonatoms, more preferably with from 7 to about 19 carbon atoms, or asubstituted arylalkyl group, wherein the substituents on the substitutedalkyl groups, substituted aryl groups, substituted arylalkyl groups,substituted alkoxy groups, substituted aryloxy groups, and substitutedarylalkyloxy groups can be (but are not limited to) hydroxy groups,amine groups, imine groups, ammonium groups, pyridine groups, pyridiniumgroups, ether groups, aldehyde groups, ketone groups, ester groups,amide groups, carboxylic acid groups, carbonyl groups, thiocarbonylgroups, sulfate groups, sulfonate groups, sulfide groups, sulfoxidegroups, phosphine groups, phosphonium groups, phosphate groups, cyanogroups, nitrile groups, mercapto groups, nitroso groups, halogen atoms,nitro groups, sulfone groups, acyl groups, acid anhydride groups, azidegroups, mixtures thereof, and the like, wherein any two or moresubstituents can be joined together to form a ring, halomethyl groups,such as fluoromethyl groups, chloromethyl groups, bromomethyl groups,and iodomethyl groups, hydroxymethyl groups, benzocyclobutene groups,including those of the formula ##STR57## phenolic groups (--φ--OH),provided that the phenolic groups are present in combination with eitherhalomethyl groups or hydroxymethyl groups; the halomethyl groups orhydroxymethyl groups can be present on the same polymer bearing thephenolic groups or on a different polymer, or on a monomeric speciespresent with the phenolic group substituted polymer; maleimide groups,such as those of the formula ##STR58## biphenylene groups, such as thoseof the formula ##STR59## 5-norbornene-2,3-dicarboximido (nadimido)groups, such as those of the formula ##STR60## alkylcarboxylate groups,such as those of the formula ##STR61## wherein R is an alkyl group(including saturated, unsaturated, and cyclic alkyl groups), preferablywith from 1 to about 30 carbon atoms, more preferably with from 1 toabout 6 carbon atoms, a substituted alkyl group, an aryl group,preferably with from 6 to about 30 carbon atoms, more preferably withfrom 1 to about 2 carbon atoms, a substituted aryl group, an arylalkylgroup, preferably with from 7 to about 35 carbon atoms, more preferablywith from 7 to about 15 carbon atoms, or a substituted arylalkyl group,wherein the substituents on the substituted alkyl, aryl, and arylalkylgroups can be (but are not limited to) alkoxy groups, preferably withfrom 1 to about 6 carbon atoms, aryloxy groups, preferably with from 6to about 24 carbon atoms, arylalkyloxy groups, preferably with from 7 toabout 30 carbon atoms, hydroxy groups, amine groups, imine groups,ammonium groups, pyridine groups, pyridinium groups, ether groups, estergroups, amide groups, carbonyl groups, thiocarbonyl groups, sulfategroups, sulfonate groups, sulfide groups, sulfoxide groups, phosphinegroups, phosphonium groups, phosphate groups, mercapto groups, nitrosogroups, sulfone groups, acyl groups, acid anhydride groups, azidegroups, and the like, wherein two or more substituents can be joinedtogether to form a ring, and the like.

The thermal sensitivity imparting groups can be present either asterminal end groups on the polymer or as groups which are pendant fromone or more monomer repeat units within the polymer chain. When thethermal sensitivity imparting groups are present as terminal end groups,one or both polymer ends can be terminated with the thermal sensitivityimparting group (or more, if the polymer is crosslinked and has morethan two termini). When the thermal sensitivity imparting groups aresubstituents on one or more monomer repeat units of the polymer, anydesired or suitable degree of substitution can be employed. Preferably,the degree of substitution is from about 1 to about 4 thermalsensitivity imparting groups per repeat monomer unit, although thedegree of substitution can be outside this range. Preferably, the degreeof substitution is from about 0.5 to about 5 milliequivalents of thermalsensitivity imparting group per gram of polymer, and more preferablyfrom about 0.75 to about 1.5 milliequivalents per gram, although thedegree of substitution can be outside this range.

The thermal sensitivity imparting groups can be placed on the polymer byany suitable or desired synthetic method. Processes for putting theabove mentioned thermal sensitivity imparting groups on polymers aredisclosed in, for example, "Polyimides," C. E. Sroog, Prog. Polym. Sci.,Vol. 16, 561-694 (1991); F. E. Arnold and L. S. Tan, Symposium on RecentAdvances in Polyimides and Other High Performance Polymers, Reno, NV(July 1987); L. S. Tan and F. E. Arnold, J. Polym. Sci. Part A, 26, 1819(1988); U.S. Pat. No. 4,973,636; and U.S. Pat. No. 4,927,907; thedisclosures of each of which are totally incorporated herein byreference.

Other procedures for placing thermally curable end groups on aromaticpolymers are disclosed in, for example, P. M. Hergenrother, J. Macromol.Sci. Rev. Macromol. Chem., C19 (1), 1-34 (1980); V. Percec and B. C.Auman, Makromol. Chem., 185, 2319 (1984); S. J. Havens, and P. M.Hergenrother, J. of Polymer Science: Polymer Chemistry Edition, 22, 3011(1984); P. M. Hergenrother, J. of Polymer Science: Polymer ChemistryEdition, 20, 3131 (1982), V. Percec, P. L. Rinaldi, and B. C. Auman,Polymer Bulletin, 10, 215 (1983); "Functional Polymers and SequentialCopolymers by Phase Transfer Catalysis, 2. Synthesis andCharacterization of Aromatic Poly(ether sulfones Containing Vinylbenzyland Ethynylbenzyl Chain Ends," V. Percec and B. C. Auman, Makromol.Chem. 185, 1867 (1984); "Functional Polymers and Sequential Copolymersby Phase Transfer Catalysis, 6. On the Phase Transfer CatalyzedWilliamson Polyetherification as a New Method for the Preparation ofAlternating Block copolymers," V. Percec, B. Auman, and P. L. Rinaldi,Polymer Bulletin, 10, 391 (1983); "Functional Polymers and SequentialCopolymers by Phase Transfer Catalysis, 3 Synthesis and Characterizationof Aromatic Poly(ether sulfone)s andPoly(oxy-2,6-dimethyl-1,4-phenylene) Containing Pendant Vinyl Groups,"V. Percec and B. C. Auman, Makromol. Chem., 185, 2319 (1984); and "PhaseTransfer Catalysis, Functional Polymers and Sequential Copolymers byPTC,5. Synthesis and Characterization of Polyformals of PolyetherSulfones," Polymer Bulletin, 10, 385 (1983); the disclosures of each ofwhich are totally incorporated herein by reference.

In some instances a functional group can behave as either aphotosensitivity-imparting group or a thermal sensitivity impartinggroup. For the polymers of the present invention having optional thermalsensitivity imparting groups thereon, at least two different groups arepresent on the polymer, one of which functions as aphotosensitivity-imparting group and one of which functions as a thermalsensitivity imparting group. Either the two groups are selected so thatthe thermal sensitivity imparting group does not react or crosslink whenexposed to actinic radiation at a level to which thephotosensitivity-imparting group is sensitive, or photocuring is haltedwhile at least some thermal sensitivity imparting groups remain intactand unreacted or uncrosslinked on the polymer. Typically (although notnecessarily) the thermal sensitivity imparting group is one which reactsat a temperature in excess of the glass transition temperature of thepolymer subsequent to crosslinking or chain extension via photoexposure.

When thermal sensitivity imparting groups are present, the polymers ofthe present invention are cured in a two-stage process which entails (a)exposing the polymer to actinic radiation, thereby causing the polymerto become crosslinked or chain extended through thephotosensitivity-imparting groups; and (b) subsequent to step (a),heating the polymer to a temperature of at least 140° C., therebycausing further crosslinking or chain extension of the polymer throughthe thermal sensitivity imparting groups.

The temperature selected for the second, thermal cure step generallydepends on the thermal sensitivity imparting group which is present onthe polymer. For example, ethynyl groups preferably are cured attemperatures of from about 150° to about 300° C. Halomethyl groupspreferably are cured at temperatures of from about 150° to about 260° C.Hydroxymethyl groups preferably are cured at temperatures of from about150° to about 250° C. Phenylethynyl phenyl groups preferably are curedat temperatures of about 350° C. Vinyl groups preferably are cured attemperatures of from about 150° to about 250° C. Allyl groups preferablyare cured at temperatures of over about 260° C. Epoxy groups preferablyare cured at temperatures of about 150° C. Maleimide groups preferablyare cured at temperatures of from about 300° to about 350° C.Benzocyclobutene groups preferably are cured at temperatures of overabout 300° C. 5-Norbornene-2,3-dicarboximido groups preferably are curedat temperatures of from about 250° to about 350° C. Vinyl ether groupspreferably are cured at temperatures of about 150° C. Phenolic groups inthe presence of hydroxymethyl or halomethyl groups preferably are curedat temperatures of from about 150° to about 180° C. Alkylcarboxylategroups preferably are cured at temperatures of from about 150° to about250° C. Curing temperatures usually do not exceed 350° or 400° C.,although higher temperatures can be employed provided that decompositionof the polymer does not occur. Higher temperature cures preferably takeplace in an oxygen-excluded environment.

Reaction of the phenylethynyl end groups serves to chain-extend thenetwork. Hydroxymethyl and halo groups are also preferred when thephotopatternable polymer has a glass transition temperature of less thanabout 150° C. Hydroxymethyl and halomethyl groups on phenolic ends areparticularly reactive and serve to chain-extend the network. The factthat this chain extension occurs at temperatures significantly in excessof the glass transition temperature of the polymer facilitates the chainextension reaction, relaxes stresses in the crosslinked film, and allowsfor the extrusion of thermally labile alkyl fragments introduced in thephotoactivation of the backbone. Phenolic end groups can be obtained byadjusting the stoichiometry of the coupling reaction in the formation ofpolyarylene ether ketones; for example, excess bisphenol A is used whenbisphenol A is the B group. Halomethyl groups are particularlypreferred. Halomethyl groups react at a temperature in excess of 150° C.and extensively crosslink the polymer by the elimination of hydrochloricacid and the formation of methylene bridges. When the photoexposedcrosslinked polymer has a glass transition temperature of less thanabout 150° C., halomethyl groups are particularly preferred. The factthat this chain extension and crosslinking occurs at temperaturessignificantly in excess of the glass transition temperature of thepolymer facilitates the chain extension reaction, relaxes stresses inthe cross-linked film, and allows for the extrusion of thermally labilealkyl fragments introduced in the photoactivation of the backbone. Thethermal reaction is believed to eliminate hydrohalic acid and to linkpolymer chains with methylene bridges. Crosslinking of the halomethylgroups begins near 150° C. and proceeds rapidly in the temperature rangeof from about 180° to about 210C.

Further information regarding photoresist compositions is disclosed in,for example, J. J. Zupancic, D. C. Blazej, T. C. Baker, and E. A.Dinkel, Polymer Preprints, 32, (2), 178 (1991); "High PerformanceElectron Negative Resist, Chloromethylated Polystyrene. A Study onMolecular Parameters," S. Imamura, T. Tamamura, and K. Harada, J. ofApplied Polymer Science, 27, 937 (1982); "Chloromethylated Polystyreneas a Dry Etching-Resistant Negative Resist for Submicron Technology", S.Imamura, J. Electrochem. Soc.: Solid-state Science and Technology,126(9), 1628 (1979); "UV curing of composites based on modifiedunsaturated polyesters," W. Shi and B. Ranby, J. of Applied PolymerScience, Vol. 51, 1129 (1994); "Cinnamates VI. Light-Sensitive Polymerswith Pendant o-,m- and p-hydroxycinnamate Moieties," F. Scigalski, M.Toczek, and J. Paczkowski, Polymer, 35, 692 (1994); and "Radiation-curedPolyurethane Methacrylate Pressure-sensitive Adhesives," G. Ansell andC. Butler, Polymer, 35 (9), 2001 (1994), the disclosures of each ofwhich are totally incorporated herein by reference.

In some instances, the terminal groups on the polymer can be selected bythe stoichiometry of the polymer synthesis. For example, when a polymeris prepared by the reaction of 4,4'-dichlorobenzophenone and bis-phenolA in the presence of potassium carbonate in N,N-dimethylacetamide, ifthe bis-phenol A is present in about 7.5 to 8 mole percent excess, theresulting polymer generally is bis-phenol A-terminated (wherein thebis-phenol A moiety may or may not have one or more hydroxy groupsthereon), and the resulting polymer typically has a polydispersity(M_(w) /M_(n)) of from about 2 to about 3.5. When the bis-phenolA-terminated polymer is subjected to further reactions to placefunctional groups thereon, such as haloalkyl groups, and/or to convertone kind of functional group, such as a haloalkyl group, to another kindof functional group, such as an unsaturated ester group, thepolydispersity of the polymer can rise to the range of from about 4 toabout 6. In contrast, if the 4,4'-dichlorobenzophenone is present inabout 7.5 to 8 mole percent excess, the reaction time is approximatelyhalf that required for the bis-phenol A excess reaction, the resultingpolymer generally is benzophenone-terminated (wherein the benzophenonemoiety may or may not have one or more chlorine atoms thereon), and theresulting polymer typically has a polydispersity of from about 2 toabout 3.5. When the benzophenone-terminated polymer is subjected tofurther reactions to place functional groups thereon, such as haloalkylgroups, and/or to convert one kind of functional group, such as ahaloalkyl group, to another kind of functional group, such as anunsaturated ester group, the polydispersity of the polymer typicallyremains in the range of from about 2 to about 3.5. Similarly, when apolymer is prepared by the reaction of 4,4'-difluorobenzophenone witheither 9,9'-bis(4-hydroxyphenyl)fluorene or bis-phenol A in the presenceof potassium carbonate in N,N-dimethylacetamide, if the4,4'-difluorobenzophenone reactant is present in excess, the resultingpolymer generally has benzophenone terminal groups (which may or may nothave one or more fluorine atoms thereon). The well-known Carothersequation can be employed to calculate the stoichiometric offset requiredto obtain the desired molecular weight. (See, for example, William H.Carothers, "An Introduction to the General Theory of CondensationPolymers," Chem. Rev., 8, 353 (1931) and J. Amer. Chem. Soc., 51, 2548(1929); see also P. J. Flory, Principles of Polymer Chemistry, CornellUniversity Press, Ithaca, N.Y. (1953); the disclosures of each of whichare totally incorporated herein by reference.) More generally speaking,during the preparation of polymers of the formula ##STR62## thestoichiometry of the polymer synthesis reaction can be adjusted so thatthe end groups of the polymer are derived from the "A" groups or derivedfrom the "B" groups. Specific functional groups can also be present onthese terminal "A" groups or "B" groups, such as ethynyl groups or otherthermally sensitive groups, hydroxy groups which are attached to thearomatic ring on an "A" or "B" group to form a phenolic moiety, halogenatoms which are attached to the "A" or "B" group, or the like.

Polymers with end groups derived from the "A" group, such asbenzophenone groups or halogenated benzophenone groups, may be preferredfor some applications because both the syntheses and some of thereactions of these materials to place substituents thereon may be easierto control and may yield better results with respect to, for example,cost, molecular weight, molecular weight range, and polydispersity(M_(w) /M_(n)) compared to polymers with end groups derived from the "B"group, such as bis-phenol A groups (having one or more hydroxy groups onthe aromatic rings thereof) or other phenolic groups. While not beinglimited to any particular theory, it is believed that the haloalkylationreaction in particular proceeds most rapidly on the phenolic tails whenthe polymer is bis-phenol A terminated. Moreover, it is believed thathalomethylated groups on phenolic-terminated polymers may beparticularly reactive to subsequent crosslinking or chain extension. Incontrast, it is generally believed that halomethylation does not takeplace on the terminal aromatic groups with electron withdrawingsubstituents, such as benzophenone, halogenated benzophenone, or thelike. The "A" group terminated materials may also function as anadhesive, and in applications such as thermal ink jet printheads, theuse of the crosslinked "A" group terminated polymer may reduce oreliminate the need for an epoxy adhesive to bond the heater plate to thechannel plate.

If desired, to reduce the amount of residual halogen in a photoresist orother composition containing the polymers of the present invention,thereby also reducing or eliminating the generation of hydrohalic acidduring a subsequent thermal curing step, any residual halogen atoms orhaloalkyl groups on the photopatternable polymer can be converted tomethoxy groups, hydroxide groups, acetoxy groups, amine groups, or thelike by any desired process, including those processes disclosedhereinabove, those disclosed in, for example, British Patent 863,702,Chem Abstr. 55, 18667b (1961), and other publications previouslyincorporated herein by reference, and the like.

The photopatternable polymer can be cured by uniform exposure to actinicradiation at wavelengths and/or energy levels capable of causingcrosslinking or chain extension of the polymer through thephotosensitivity-imparting groups. Alternatively, the photopatternablepolymer is developed by imagewise exposure of the material to radiationat a wavelength and/or at an energy level to which thephotosensitivity-imparting groups are sensitive. Typically, aphotoresist composition will contain the photopatternable polymer, anoptional solvent for the photopatternable polymer, an optionalsensitizer, and an optional photoinitiator. Solvents may be particularlydesirable when the uncrosslinked photopatternable polymer has a highT_(g). The solvent and photopatternable polymer typically are present inrelative amounts of from 0 to about 99 percent by weight solvent andfrom about 1 to 100 percent polymer, preferably are present in relativeamounts of from about 20 to about 60 percent by weight solvent and fromabout 40 to about 80 percent by weight polymer, and more preferably arepresent in relative amounts of from about 30 to about 60 percent byweight solvent and from about 40 to about 70 percent by weight polymer,although the relative amounts can be outside these ranges.

Sensitizers absorb light energy and facilitate the transfer of energy tounsaturated bonds which can then react to crosslink or chain extend theresin. Sensitizers frequently expand the useful energy wavelength rangefor photoexposure, and typically are aromatic light absorbingchromophores. Sensitizers can also lead to the formation ofphotoinitiators, which can be free radical or ionic. When present, theoptional sensitizer and the photopatternable polymer typically arepresent in relative amounts of from about 0.1 to about 20 percent byweight sensitizer and from about 80 to about 99.9 percent by weightphotopatternable polymer, and preferably are present in relative amountsof from about 1 to about 10 percent by weight sensitizer and from about90 to about 99 percent by weight photopatternable polymer, although therelative amounts can be outside these ranges.

Photoinitiators generally generate ions or free radicals which initiatepolymerization upon exposure to actinic radiation When present, theoptional photoinitiator and the photopatternable polymer typically arepresent in relative amounts of from about 0.1 to about 20 percent byweight photoinitiator and from about 80 to about 99.9 percent by weightphotopatternable polymer, and preferably are present in relative amountsof from about 1 to about 10 percent by weight photoinitiator and fromabout 90 to about 99 percent by weight photopatternable polymer,although the relative amounts can be outside these ranges.

A single material can also function as both a sensitizer and aphotoinitiator.

Examples of specific sensitizers and photoinitiators include Michier'sketone (Aldrich Chemical Co.), Darocure 1173, Darocure 4265, Irgacure184, Irgacure 261, and Irgacure 907 (available from Ciba-Geigy, Ardsley,N.Y.), and mixtures thereof. Further background material on initiatorsis disclosed in, for example, Ober et al., J.M.S.-Pure Appl. Chem., A30(12), 877-897 (1993); G. E. Green, B. P. Stark, and S. A. Zahir,"Photocrosslinkable Resin Systems," J. Macro. Sci.-Revs. Macro. Chem.,C21(2), 187 (1981); H. F. Gruber, "Photoinitiators for Free RadicalPolymerization," Prog. Polym. Sci., Vol. 17, 953 (1992); Johann G.Kloosterboer, "Network Formation by Chain CrosslinkingPhotopolymerization and Its Applications in Electronics," Advances inPolymer Science, 89, Springer-Verlag Berlin Heidelberg (1988); and"Diaryliodonium Salts as Thermal Initiators of Cationic Polymerization,"J. V. Crivello, T. P. Lockhart, and J. L. Lee, J. of Polymer Science:Polymer Chemistry Edition, 21, 97 (1983), the disclosures of each ofwhich are totally incorporated herein by reference. Sensitizers areavailable from, for example, Aldrich Chemical Co., Milwaukee, Wis., andPfaltz and Bauer, Waterberry, Conn. Benzophenone and its derivatives canfunction as photosensitizers. Triphenylsulfonium and diphenyl iodoniumsalts are examples of typical cationic photoinitiators.

Inhibitors may also optionally be present in the photoresist containingthe photopatternable polymer. Examples of suitable inhibitors includeMEHQ, a methyl ether of hydroquinone, of the formula ##STR63##t-butylcatechol, of the formula ##STR64## hydroquinone, of the formula##STR65## and the like, the inhibitor typically present in an amount offrom about 500 to about 1,500 parts per million by weight of aphotoresist solution containing about 40 percent by weight polymersolids, although the amount can be outside this range.

The halomethylated polymers of the present invention are generallypatternable with electron beam, ultraviolet, or x-ray radiation. Typicalsuitable wavelengths for ultraviolet radiation are from about 200 toabout 365 nanometers, and preferably deep uv radiation of from about 200to about 260 nanometers, although the wavelength can be outside thisrange. Typical suitable energy levels for e-beam radiation are fromabout 600 to about 2,000 megarads, and preferably about 1,000 megarads,although the energy level can be outside this range. Typical suitablex-ray radiation levels are from about 100 to about 2,500 milliJoules persquare centimeter, or from about 600 to about 2,000 rads, although theradiation level can be outside this range, Suitable imaging apparatusfor e-beam exposure includes Van de Graaf generators and other highenergy particle accelerators, such as those available from EnergyScience, Woburn Mass., Radionics, Woburn, Mass. scanning electronmicroscope equipment, such as that available from Siemens AG, and thelike. Other suitable e-beam sources include 20 KV exposures using a LaB₆electron gun at 0.24 megarads per hour, and an RCA Transmission ElectronMicroscope Model 3G modified to provide a source between 22 and 44 KeVelectrons. Suitable imaging apparatus for ultraviolet exposure includesequipment available from Adcotech Corp., Advance Process Supply Co.,Argus International, Arthur Blank & Co., Inc., Chemcut Corp., ChemicalEtching Equipment & Supply Co., The Christopher Group, Cirplex/QualityAssurance Marketing Div., Colight, Inc., DGE, Inc., Dyna/Pert, Div. ofEmhart Corp., Dyonics Inc., Industrial Div., Fusion Systems Corp., GyrexCorp., subsidiary of Allied Chemical Co., Hybrid Technology Group, Inc.,International Printing Machines Corp., Geo. Koch & Sons, Ashdee Div.,Kras Corp., Machine Technology, Inc., Magnum Technology Inc., NationwideCircuit Products, Stenning Instruments Inc., UV Process Supply, Inc.,Uvexs, Inc., UVP, Inc., Ultraviolet Products, Xenon Corp., and the like.Any source of x-ray radiation can be used for x-ray imaging apparatus.Further information regarding suitable exposure apparatus is disclosedin, for example, Reactive Cure Systems: UV-IR-EB, CAPTAN AssociatesInc., PO Box 504, Brick, N.J. (1994), and in "Fundamental Aspects ofElectron Beam Lithography," G. M. Venkatesh et al., Polymer Preprints,22(2), 335 (1981), the disclosures of each of which are totallyincorporated herein by reference.

While not being limited to any particular theory, it is believed thatexposure to, for example, e-beam, ultraviolet, or x-ray radiationgenerally results in free radical cleavage of the halogen atom from themethyl group to form a benzyl radical. Crosslinking or chain extensionthen occurs at the "long" bond sites as illustrated below for thechloromethylated material: ##STR66##

Many of the photosensitivity-imparting groups which are indicated aboveas being capable of enabling crosslinking or chain extension of thepolymer upon exposure to actinic radiation can also enable crosslinkingor chain extension of the polymer upon exposure to elevatedtemperatures; thus the polymers of the present invention can also, ifdesired, be used in applications wherein thermal curing is employed.

In all of the above reactions and substitutions illustrated above forthe polymer of the formula ##STR67## it is to be understood thatanalogous reactions and substitutions will occur for the polymer of theformula ##STR68##

Photopatternable halomethylated polymers of the present invention can beused as components in ink jet printheads. The printheads of the presentinvention can be of any suitable configuration. An example of a suitableconfiguration, suitable in this instance for thermal ink jet printing,is illustrated schematically in FIG. 1, which depicts an enlarged,schematic isometric view of the front face 29 of a printhead 10 showingthe array of droplet emitting nozzles 27. Referring also to FIG. 2,discussed later, the lower electrically insulating substrate or heatingelement plate 28 has the heating elements 34 and addressing electrodes33 patterned on surface 30 thereof, while the upper substrate or channelplate 31 has parallel grooves 20 which extend in one direction andpenetrate through the upper substrate front face edge 29. The other endof grooves 20 terminate at slanted wall 21, the floor 41 of the internalrecess 24 which is used as the ink supply manifold for the capillaryfilled ink channels 20, has an opening 25 therethrough for use as an inkfill hole. The surface of the channel plate with the grooves are alignedand bonded to the heater plate 28, so that a respective one of theplurality of heating elements 34 is positioned in each channel, formedby the grooves and the lower substrate or heater plate. Ink enters themanifold formed by the recess 24 and the lower substrate 28 through thefill hole 25 and by capillary action, fills the channels 20 by flowingthrough an elongated recess 38 formed in the thick film insulative layer18. The ink at each nozzle forms a meniscus, the surface tension ofwhich prevents the ink from weeping therefrom. The addressing electrodes33 on the lower substrate or channel plate 28 terminate at terminals 32.The upper substrate or channel plate 31 is smaller than that of thelower substrate in order that the electrode terminals 32 are exposed andavailable for wire bonding to the electrodes on the daughter board 19,on which the printhead 10 is permanently mounted. Layer 18 is a thickfilm passivation layer, discussed later, sandwiched between the upperand lower substrates. This layer is etched to expose the heatingelements, thus placing them in a pit, and is etched to form theelongated recess to enable ink flow between the manifold 24 and the inkchannels 20. In addition, the thick film insulative layer is etched toexpose the electrode terminals.

A cross sectional view of FIG. 1 is taken along view line 2--2 throughone channel and shown as FIG. 2 to show how the ink flows from themanifold 24 and around the end 21 of the groove 20 as depicted by arrow23. As is disclosed in U.S. Pat. No. 4,638,337, U.S. Pat. No. 4,601,777,and U.S. Pat. No. Re. 32,572, the disclosures of each of which aretotally incorporated herein by reference, a plurality of sets of bubblegenerating heating elements 34 and their addressing electrodes 33 can bepatterned on the polished surface of a single side polished (100)silicon wafer. Prior to patterning, the multiple sets of printheadelectrodes 33, the resistive material that serves as the heatingelements 34, and the common return 35, the polished surface of the waferis coated with an underglaze layer 39 such as silicon dioxide, having atypical thickness of from about 5,000 Angstroms to about 2 microns,although the thickness can be outside this range. The resistive materialcan be a doped polycrystalline silicon, which can be deposited bychemical vapor deposition (CVD) or any other well known resistivematerial such as zirconium boride (ZrB₂). The common return and theaddressing electrodes are typically aluminum leads deposited on theunderglaze and over the edges of the heating elements. The common returnends or terminals 37 and addressing electrode terminals 32 arepositioned at predetermined locations to allow clearance for wirebonding to the electrodes (not shown) of the daughter board 19, afterthe channel plate 31 is attached to make a printhead. The common return35 and the addressing electrodes 33 are deposited to a thicknesstypically of from about 0.5 to about 3 microns, although the thicknesscan be outside this range, with the preferred thickness being 1.5microns.

If polysilicon heating elements are used, they may be subsequentlyoxidized in steam or oxygen at a relatively high temperature, typicallyabout 1,100° C. although the temperature can be above or below thisvalue, for a period of time typically of from about 50 to about 80minutes, although the time period can be outside this range, prior tothe deposition of the aluminum leads, in order to convert a smallportion of the polysilicon to SiO₂. In such cases, the heating elementsare thermally oxidized to achieve an overglaze (not shown) of SiO₂ witha thickness typically of from about 500 Angstroms to about 1 micron,although the thickness can be outside this range, which has goodintegrity with substantially no pinholes.

In one embodiment, polysilicon heating elements are used and an optionalsilicon dioxide thermal oxide layer 17 is grown from the polysilicon inhigh temperature steam. The thermal oxide layer is typically grown to athickness of from about 0.5 to about 1 micron, although the thicknesscan be outside this range, to protect and insulate the heating elementsfrom the conductive ink. The thermal oxide is removed at the edges ofthe polysilicon heating elements for attachment of the addressingelectrodes and common return, which are then patterned and deposited. Ifa resistive material such as zirconium boride is used for the heatingelements, then other suitable well known insulative materials can beused for the protective layer thereover. Before electrode passivation, atantalum (Ta) layer (not shown) can be optionally deposited, typicallyto a thickness of about 1 micron, although the thickness can be above orbelow this value, on the heating element protective layer 17 for addedprotection thereof against the cavitational forces generated by thecollapsing ink vapor bubbles during printhead operation. The tantalumlayer is etched off all but the protective layer 17 directly over theheating elements using, for example, CF₄ /O₂ plasma etching. Forpolysilicon heating elements, the aluminum common return and addressingelectrodes typically are deposited on the underglaze layer and over theopposing edges of the polysilicon heating elements which have beencleared of oxide for the attachment of the common return and electrodes.

For electrode passivation, a film 16 is deposited over the entire wafersurface, including the plurality of sets of heating elements andaddressing electrodes. The passivation film 16 provides an ion barrierwhich will protect the exposed electrodes from the ink. Examples ofsuitable ion barrier materials for passivation film 16 includepolyimide, plasma nitride, phosphorous doped silicon dioxide, materialsdisclosed herein as being suitable for insulative layer 18, and thelike, as well as any combinations thereof. An effective ion barrierlayer is generally achieved when its thickness is from about 1000Angstroms to about 10 microns, although the thickness can be outsidethis range. In 300 dpi printheads, passivation layer 16 preferably has athickness of about 3 microns, although the thickness can be above orbelow this value. In 600 dpi printheads, the thickness of passivationlayer 16 preferably is such that the combined thickness of layer 16 andlayer 18 is about 25 microns, although the thickness can be above orbelow this value. The passivation film or layer 16 is etched off of theterminal ends of the common return and addressing electrodes for wirebonding later with the daughter board electrodes. This etching of thesilicon dioxide film can be by either the wet or dry etching method.Alternatively, the electrode passivation can be by plasma depositedsilicon nitride (Si₃ N₄).

Next, a thick film type insulative layer 18, of a polymeric materialdiscussed in further detail herein, is formed on the passivation layer16, typically having a thickness of from about 10 to about 100 micronsand preferably in the range of from about 25 to about 50 microns,although the thickness can be outside these ranges. Even morepreferably, in 300 dpi printheads, layer 18 preferably has a thicknessof about 30 microns, and in 600 dpi printheads, layer 18 preferably hasa thickness of from about 20 to about 22 microns, although otherthicknesses can be employed. The insulative layer 18 isphotolithographically processed to enable etching and removal of thoseportions of the layer 18 over each heating element (forming recesses26), the elongated recess 38 for providing ink passage from the manifold24 to the ink channels 20, and over each electrode terminal 32, 37. Theelongated recess 38 is formed by the removal of this portion of thethick film layer 18. Thus, the passivation layer 16 alone protects theelectrodes 33 from exposure to the ink in this elongated recess 38.Optionally, if desired, insulative layer 18 can be applied as a seriesof thin layers of either similar or different composition. Typically, athin layer is deposited, photoexposed, partially cured, followed bydeposition of the next thin layer, photoexposure, partial curing, andthe like. The thin layers constituting thick film insulative layer 18contain a polymer of the formula indicated hereinabove. In oneembodiment of the present invention, a first thin layer is applied tocontact layer 16, said first thin layer containing a mixture of apolymer of the formula indicated hereinabove and an epoxy polymer,followed by photoexposure, partial curing, and subsequent application ofone or more successive thin layers containing a polymer of the formulaindicated hereinabove.

FIG. 3 is a similar view to that of FIG. 2 with a shallowanisotropically etched groove 40 in the heater plate, which is silicon,prior to formation of the underglaze 39 and patterning of the heatingelements 34, electrodes 33 and common return 35. This recess 40 permitsthe use of only the thick film insulative layer 18 and eliminates theneed for the usual electrode passivating layer 16. Since the thick filmlayer 18 is impervious to water and relatively thick (typically fromabout 20 to about 40 microns, although the thickness can be outside thisrange), contamination introduced into the circuitry will be much lessthan with only the relatively thin passivation layer 16 well known inthe art. The heater plate is a fairly hostile environment for integratedcircuits. Commercial ink generally entails a low attention to purity. Asa result, the active part of the heater plate will be at elevatedtemperature adjacent to a contaminated aqueous ink solution whichundoubtedly abounds with mobile ions. In addition, it is generallydesirable to run the heater plate at a voltage of from about 30 to about50 volts, so that there will be a substantial field present. Thus, thethick film insulative layer 18 provides improved protection for theactive devices and provides improved protection, resulting in longeroperating lifetime for the heater plate.

When a plurality of lower substrates 28 are produced from a singlesilicon wafer, at a convenient point after the underglaze is deposited,at least two alignment markings (not shown) preferably arephotolithographically produced at predetermined locations on the lowersubstrates 28 which make up the silicon wafer. These alignment markingsare used for alignment of the plurality of upper substrates 31containing the ink channels. The surface of the single sided wafercontaining the plurality of sets of heating elements is bonded to thesurface of the wafer containing the plurality of ink channel containingupper substrates subsequent to alignment.

As disclosed in U.S. Pat. No. 4,601,777 and U.S. Pat. No. 4,638,337, thedisclosures of each of which are totally incorporated herein byreference, the channel plate is formed from a two side polished, (100)silicon wafer to produce a plurality of upper substrates 31 for theprinthead. After the wafer is chemically cleaned, a pyrolytic CVDsilicon nitride layer (not shown) is deposited on both sides. Usingconventional photolithography, a via for fill hole 25 for each of theplurality of channel plates 31 and at least two vias for alignmentopenings (not shown) at predetermined locations are printed on one waferside. The silicon nitride is plasma etched off of the patterned viasrepresenting the fill holes and alignment openings. A potassiumhydroxide (KOH) anisotropic etch can be used to etch the fill holes andalignment openings. In this case, the (111) planes of the (100) wafertypically make an angle of about 54.7 degrees with the surface of thewafer. The fill holes are small square surface patterns, generally ofabout 20 mils (500 microns) per side, although the dimensions can beabove or below this value, and the alignment openings are from about 60to about 80 mils (1.5 to 3 millimeters) square, although the dimensionscan be outside this range. Thus, the alignment openings are etchedentirely through the 20 mil (0.5 millimeter) thick wafer, while the fillholes are etched to a terminating apex at about halfway through tothree-quarters through the wafer. The relatively small square fill holeis invariant to further size increase with continued etching so that theetching of the alignment openings and fill holes are not significantlytime constrained.

Next, the opposite side of the wafer is photolithographically patterned,using the previously etched alignment holes as a reference to form therelatively large rectangular recesses 24 and sets of elongated, parallelchannel recesses that will eventually become the ink manifolds andchannels of the printheads. The surface 22 of the wafer containing themanifold and channel recesses are portions of the original wafer surface(covered by a silicon nitride layer) on which an adhesive, such as athermosetting epoxy, will be applied later for bonding it to thesubstrate containing the plurality of sets of heating elements. Theadhesive is applied in a manner such that it does not run or spread intothe grooves or other recesses. The alignment markings can be used with,for example, a vacuum chuck mask aligner to align the channel wafer onthe heating element and addressing electrode wafer. The two wafers areaccurately mated and can be tacked together by partial curing of theadhesive.

Alternatively, the heating element and channel wafers can be givenprecisely diced edges and then manually or automatically aligned in aprecision jig. Alignment can also be performed with an infraredaligner-bonder, with an infrared microscope using infrared opaquemarkings on each wafer to be aligned, or the like. The two wafers canthen be cured in an oven or laminator to bond them together permanently.The channel wafer can then be milled to produce individual uppersubstrates. A final dicing cut, which produces end face 29, opens oneend of the elongated groove 20 producing nozzles 27. The other ends ofthe channel groove 20 remain closed by end 21. However, the alignmentand bonding of the channel plate to the heater plate places the ends 21of channels 20 directly over elongated recess 38 in the thick filminsulative layer 18 as shown in FIG. 2 or directly above the recess 40as shown in FIG. 3 enabling the flow of ink into the channels from themanifold as depicted by arrows 23. The plurality of individualprintheads produced by the final dicing are bonded to the daughter boardand the printhead electrode terminals are wire bonded to the daughterboard electrodes.

In one embodiment, a heater wafer with a phosphosilicate glass layer isspin coated with a solution of Z6020 adhesion promoter (0.01 weightpercent in 95 parts methanol and 5 parts water, Dow Corning) at 3000revolutions per minute for 10 seconds and dried at 100° C. for between 2and 10 minutes. The wafer is then allowed to cool at 25° C. for 5minutes before spin coating the photoresist containing thephotopatternable polymer onto the wafer at between 1,000 and 3,000revolutions per minute for between 30 and 60 seconds. The photoresistsolution is made by dissolving polyarylene ether ketone with 1.5halomethyl groups per repeat unit and a weight average molecular weightof 8,000 in N-methylpyrrolidinone at 40 weight percent solids withMichier's ketone (1.2 parts ketone per every 10 parts of 40 weightpercent solids polymer solution). The film is heated (soft baked) in anoven for between 10 and 15 minutes at 70° C. After cooling to 25° C.over 5 minutes, the film is covered with a mask and exposed to electronbeam radiation, x-ray radiation, or deep UV radiation, such as a KrFdeep UV CW lamp with output at 22 to 26 milliJoules per squarecentimeter at 253.7 nanometers. The exposed wafer is then heated at 70°C. for 2 minutes post exposure bake, followed by cooling to 25° C. over5 minutes. The film is developed with a developer mixture containing 60percent by volume cyclohexanone and 40 percent by volume chloroform,washed with hexane, and then dried at 70° C. for 2 minutes. A seconddeveloper/wash cycle is carried out if necessary to obtain a wafer withclean features. The processed wafer is transferred to an oven at 25° C.,and the oven temperature is raised from 25 to 90° C. at 2° C. perminute. The temperature is maintained at 90° C. for 2 hours, and thenincreased to 260° C. at 2° C. per minute. The oven temperature ismaintained at 260° C. for 2 hours and then the oven is turned off andthe temperature is allowed to cool gradually to 25° C. When thermal cureof the photoresist films is carried out under inert atmosphere, such asnitrogen or one of the noble gases, such as argon, neon, krypton, xenon,or the like, there is markedly reduced oxidation of the developed filmand improved thermal and hydrolytic stability of the resultant devices.Moreover, adhesion of developed photoresist film is improved to theunderlying substrate. If a second layer is spin coated over the firstlayer, the heat cure of the first developed layer can be stopped between80° and 260° C. before the second layer is spin coated onto the firstlayer. A second thicker layer is deposited by repeating the aboveprocedure a second time. This process is intended to be a guide in thatprocedures can be outside the specified conditions depending on filmthickness and photoresist molecular weight. Films at 30 microns havebeen developed with clean features at 600 dots per inch.

For best results with respect to well-resolved features and high aspectratios, photoresist compositions of the present invention are free ofparticulates prior to coating onto substrates. In one preferredembodiment, the photoresist composition containing the photopatternablepolymer is subjected to filtration through a 2 micron nylon filter cloth(available from Tetko). The photoresist solution is filtered through thecloth under yellow light or in the dark as a solution containing fromabout 30 to about 60 percent by weight solids using compressed air (upto about 60 psi) and a pressure filtration funnel. No dilution of thephotoresist solution is required, and concentrations of an inhibitor(such as, for example, MEHQ) can be as low as, for example, 500 partsper million or less by weight without affecting shelf life. No build inmolecular weight of the photopatternable polymer is observed during thisfiltration process. While not being limited to any particular theory, itis believed that in some instances, such as those when unsaturated estergroups are present on the photopolymerizable polymer, compressed airyields results superior to those obtainable with inert atmospherebecause oxygen in the compressed air acts as an effective inhibitor forthe free radical polymerization of unsaturated ester groups such asacrylates and methocrylates.

The halomethylated polymer insulative layer, because of its relativelylow polarity, is highly resistant to attack from inks commonly used inthermal ink jet printing processes, including inks of relatively high pHvalues of from about 8.5 to about 10.

The printhead illustrated in FIGS. 1 through 3 constitutes a specificembodiment of the present invention. Any other suitable printheadconfiguration comprising ink-bearing channels terminating in nozzles onthe printhead surface can also be employed with the materials disclosedherein to form a printhead of the present invention.

In a particularly preferred embodiment, the photopatternable polymer isadmixed with an epoxy resin in relative amounts of from about 75 partsby weight photopatternable polymer and about 25 parts by weight epoxyresin to about 90 parts by weight photopatternable polymer and about 10parts by weight epoxy resin. Examples of suitable epoxy resins includeEPON 1001F, available from Shell Chemical Company, Houston, Tex.,believed to be of the formula ##STR69## and the like, as well asmixtures thereof. Curing agents such as the "Y" curative(meta-phenylenediamine) and the like, as well as mixtures thereof, canbe used to cure the epoxy resin at typical relative amounts of about 10weight percent curative per gram of epoxy resin solids. Processconditions for the epoxy resin blended with the photopatternable polymerare generally similar to those used to process the photoresist withoutepoxy resin. Preferably, the epoxy or epoxy blend is selected so thatits curing conditions are different from the conditions employed toapply, image, develop, and cure the photopatternable polymer. Selectivestepwise curing allows development of the photoresist film before curingthe epoxy resin to prevent unwanted epoxy residues on the device.Incorporation of the epoxy resin into the photopatternable polymermaterial improves the adhesion of the photopatternable layer to theheater plate. Subsequent to imaging and during cure of thephotopatternable polymer, the epoxy reacts with the heater layer to formstrong chemical bonds with that layer, improving adhesive strength andsolvent resistance of the interface. The presence of the epoxy may alsoimprove the hydrophilicity of the photopatternable polymer and thus mayimprove the wetting properties of the layer, thereby improving therefill characteristics of the printhead.

The present invention also encompasses printing processes withprintheads according to the present invention. One embodiment of thepresent invention is directed to an ink jet printing process whichcomprises (1) preparing an ink jet printhead comprising a plurality ofchannels, wherein the channels are capable of being filled with ink froman ink supply and wherein the channels terminate in nozzles on onesurface of the printhead, said preparation being according to theprocess of the present invention; (2) filling the channels with an ink;and (3) causing droplets of ink to be expelled from the nozzles onto areceiver sheet in an image pattern. A specific embodiment of thisprocess is directed to a thermal ink jet printing process, wherein thedroplets of ink are caused to be expelled from the nozzles by heatingselected channels in an image pattern. The droplets can be expelled ontoany suitable receiver sheet, such as fabric, plain paper such as Xerox®4024 or 4010, coated papers, transparency materials, or the like.

Specific embodiments of the invention will now be described in detail.These examples are intended to be illustrative, and the invention is notlimited to the materials, conditions, or process parameters set forth inthese embodiments. All parts and percentages are by weight unlessotherwise indicated.

EXAMPLE I

A polyarylene ether ketone of the formula ##STR70## wherein n is betweenabout 2 and about 30 (hereinafter referred to as poly(4-CPK-BPA)) wasprepared as follows. A 5 liter, 3-neck round-bottom flask equipped witha Dean-Stark (Barrett) trap, condenser, mechanical stirrer, argon inlet,and stopper was situated in a silicone oil bath.4,4'-Dichlorobenzophenone (Aldrich 11,370, Aldrich Chemical Co.,Milwaukee, Wis., 250 grams), bis-phenol A (Aldrich 23,965-8, 244.8grams), potassium carbonate (327.8 grams), anhydrousN,N-dimethylacetamide (1,500 milliliters), and toluene (275 milliliters)were added to the flask and heated to 175° C. (oil bath temperature)while the volatile toluene component was collected and removed. After 48hours of heating at 175° C. with continuous stirring, the reactionmixture was filtered to remove insoluble salts, and the resultantsolution was added to methanol (5 gallons) to precipitate the polymer.The polymer was isolated by filtration, and the wet filter cake waswashed with water (3 gallons) and then with methanol (3 gallons). Theyield was 360 grams of vacuum dried polymer. The molecular weight of thepolymer was determined by gel permeation chromatography (gpc) (elutionsolvent was tetrahydrofuran) with the following results: M_(n) 3,430,M_(peak) 5,380, M_(w) 3,600, M_(z) 8,700, and M_(z+1) 12,950. The glasstransition temperature of the polymer was between 125° and 155° C. asdetermined using differential scanning calorimetry at a heating rate of20° C. per minute dependent on molecular weight. Solution cast filmsfrom methylene chloride were clear, tough, and flexible. As a result ofthe stoichiometries used in the reaction, it is believed that thispolymer had end groups derived from bis-phenol A.

EXAMPLE II

A polyarylene ether ketone of the formula ##STR71## wherein n is betweenabout 6 and about 30 (hereinafter referred to as poly(4-CPK-BPA)) wasprepared as follows. A 1 liter, 3-neck round-bottom flask equipped witha Dean-Stark (Barrett) trap, condenser, mechanical stirrer, argon inlet,and stopper was situated in a silicone oil bath.4,4'-Dichlorobenzophenone (Aldrich 11,370, Aldrich Chemical Co.,Milwaukee, Wis., 50 grams), bis-phenol A (Aldrich 23,965-8, 48.96grams), potassium carbonate (65.56 grams), anhydrousN,N-dimethylacetamide (300 milliliters), and toluene (55 milliliters)were added to the flask and heated to 175° C. (oil both temperature)while the volatile toluene component was collected and removed. After 24hours of heating at 175° C. with continuous stirring, an aliquot of thereaction product that had been precipitated into methanol was analyzedby gel permeation chromatography (gpc) (elution solvent wastetrahydrofuran) with the following results: M_(n) 4464, M_(peak) 7583,M_(w) 7927, M_(z) 12,331, and M_(z+1) , 16,980. After 48 hours at 175°C. with continuous stirring, the reaction mixture was filtered to removepotassium carbonate and precipitated into methanol (2 gallons). Thepolymer (poly(4-CPK-BPA)) was isolated in 86% yield after filtration anddrying in vacuo. GPC analysis was as follows: M_(n) , 5347, M_(peak)16,126, M_(w) 15,596, M_(z) 29,209, and M_(z+1) 42,710. The glasstransition temperature of the polymer was about 120°±0° C. as determinedusing differential scanning calorimetry at a heating rate of 20° C. perminute. Solution cast films from methylene chloride were clear, tough,and flexible. As a result of the stoichiometries used in the reaction,it is believed that this polymer had end groups derived from bis-phenolA.

EXAMPLE III

A solution of chloromethyl ether in methyl acetate was made by adding282.68 grams (256 milliliters) of acetyl chloride to a mixture ofdimethoxy methane (313.6 grams, 366.8 milliliters) and methanol (10milliliters) in a 5 liter 3-neck round-bottom flask equipped with amechanical stirrer, argon inlet, reflux condenser, and addition funnel.The solution was diluted with 1,066.8 milliliters of1,1,2,2-tetrachloroethane and then tin tetrachloride (2.4 milliliters)was added via a gas-tight syringe along with 1,1,2,2-tetrachloroethane(133.2 milliliters) using an addition funnel. The reaction solution washeated to 500° C. Thereafter, a solution of poly(4-CPK-BPA) prepared asdescribed in Example I (160.8 grams) in 1,000 milliliters oftetrachloroethane was added rapidly. The reaction mixture was thenheated to reflux with an oil bath set at 110° C. After four hours refluxwith continuous stirring, heating was discontinued and the mixture wasallowed to cool to 25° C. The reaction mixture was transferred in stagesto a 2 liter round bottom flask and concentrated using a rotaryevaporator with gentle heating up to 50° C. while reduced pressure wasmaintained with a vacuum pump trapped with liquid nitrogen. Theconcentrate was added to methanol (4 gallons) to precipitate the polymerusing a Waring blender. The polymer was isolated by filtration andvacuum dried to yield 200 grams of poly(4-CPK-BPA) with 1.5 chloromethylgroups per repeat unit as identified using ¹ H NMR spectroscopy. Whenthe same reaction was carried out for 1, 2, 3, and 4 hours, the amountof chloromethyl groups per repeat unit was 0.76, 1.09, 1.294, and 1.496,respectively.

Solvent free polymer was obtained by reprecipitation of he polymer (75grams) in methylene chloride (500 grams) into ethanol (3 gallons)followed by filtration and vacuum drying to yield 70.5 grams (99.6%theoretical yield) of solvent free polymer.

When the reaction was carried out under similar conditions except that80.4 grams of poly(4-CPK-BPA) was used instead of 160.8 grams and theamounts of the other reagents were the some as indicated above, thepolymer is formed with 1.31, 1.50, 1.75, and 2 chloromethyl groups perrepeat unit in 1, 2, 3, and 4 hours, respectively, at 110° C. (oil bathtemperature).

When 241.2 grams of poly(4-CPK-BPA) was used instead of 160.8 grams withthe other reagents fixed, poly(CPK-BPA) was formed with 0.79, 0, 90,0.98, 1.06, 1.22, and 1.38 chloromethyl groups per repeat unit in 1, 2,3, 4, 5, and 6 hours, respectively, at 110° C. (oil bath temperature).

When 321.6 grams of poly(4-CPK-BPA) was used instead of 160.8 grams withthe other reagents fixed, poly(CPK-BPA) was formed with 0.53, 0.59,0.64, 0.67, 0.77, 0.86, 0.90, and 0.97 chloromethyl groups per repeatunit in 1, 2, 3, 4, 5, 6, 7, and 8 hours, respectively, at 110° C. (oilbath temperature).

EXAMPLE IV

A solution of chloromethyl ether in methyl acetate was made by adding35.3 grams of acetyl chloride to a mixture of dimethoxy methane (45milliliters) and methanol (1.25 milliliters) in a 500 milliliter 3-neckround-bottom flask equipped with a mechanical stirrer, argon inlet,reflux condenser, and addition funnel. The solution was diluted with 150milliliters of 1,1,2,2-tetrachloroethane and then tin tetrachloride (0.3milliliters) was added via syringe. The solution was heated to refluxwith an oil bath set at 110° C. Thereafter, a solution ofpoly(4-CPK-BPA) prepared as described in Example I (10 grams) in 125milliliters of tetrachloroethane was added over 8 minutes. After twohours reflux with continuous stirring, heating was discontinued and themixture was allowed to cool to 25° C. The reaction mixture wastransferred to a rotary evaporator with gentle heating at between 50°and 55° C. After 1 hour, when most of the volatiles had been removed,the reaction mixture was added to methanol (25 milliliter solution to 3cups of methanol) to precipitate the polymer using a Waring blender. Theprecipitated polymer was collected by filtration, washed with methanol,and air-dried to yield 13 grams of off-white powder. The polymer hadabout 1.5 CH₂ Cl groups per repeat unit.

EXAMPLE V

Heater wafers with phosphosilicate glass layers were spin coated with asolution of Z6020 adhesion promoter (0.01 weight percent in 95 partsmethanol and 5 parts water, Dow Corning) at 3000 revolutions per minutefor 10 seconds and dried at 100° C. for between 2 and 10 minutes. Thewafers were then allowed to cool at 25° C. for 5 minutes before spincoating a photoresist containing a chloromethylated polyarylene etherketone prepared as described in Example II onto the wafer at between1,000 and 3,000 revolutions per minute for between 30 and 60 seconds.The photoresist solution was made by dissolving polyarylene ether ketonewith 1 chloromethyl group per repeat unit and a weight average molecularweight of 11,000 in N-methylpyrrolidinone at 40 weight percent solids.The films were heated (soft baked) in an oven at 80° C. for 15 minutes,followed by cooling to room temperature. Thereafter, the films werecovered with masks and one set of coated glass slides was exposed to theelectron beam of a Hitachi scanning electron microscope (SEM) (ModelS-2300) operated from about 8 to about 40 KV, with from about 12 toabout 22 KV being preferred. A second set of coated glass slides wasexposed to a 260 nanometer ultraviolet laser beam from a Molectron Corp.10 Watt YAG laser with pulses up to 10 kiloHertz at 15 nanoseconds orless per pulse and with up to 1 Joule per pulse. Subsequent to imagewiseexposure, both sets of glass slides were annealed in an oven at 80° C.for 2 minutes, followed by cooling to room temperature and developmentby washing with a mixture containing 60 percent by volume cyclohexanoneand 40 percent by volume chloroform. The developed slides were thenwashed with hexane and cured in an oven at 250° C. for 2 hours to ensurecomplete polymerization of the resist. The developed resists exhibitedvery well defined features.

EXAMPLE VI

A polyarylene ether ketone of the formula ##STR72## wherein n is betweenabout 6 and about 30 (hereinafter referred to as poly(4-CPK-BPA)) wasprepared as follows. A 1 liter, 3-neck round-bottom flask equipped witha Dean-Stark (Barrett) trap, condenser, mechanical stirrer, argon inlet,and stopper was situated in a silicone oil bath.4,4'-Dichlorobenzophenone (Aldrich 11,370, Aldrich Chemical Co.,Milwaukee, Wis., 53.90 grams), bis-phenol A (Aldrich 23,965-8, 45.42grams), potassium carbonate (65.56 grams), anhydrousN,N-dimethylacetamide (300 milliliters), and toluene (55 milliliters)were added to the flask and heated to 175° C. (oil bath temperature)while the volatile toluene component was collected and removed. After 24hours of heating at 175° C. with continuous stirring, the reactionmixture was filtered to remove potassium carbonate and precipitated intomethanol (2 gallons). The polymer (poly(4-CPK-BPA)) was isolated in 86%yield after filtration and drying in vacuo. GPC analysis was as follows:M_(n) 4,239, M_(peak) 9,164, M_(w) 10,238, M_(z) 18,195, and M_(z+1)25,916. Solution cast films from methylene chloride were clear, tough,and flexible. As a result of the stoichiometries used in the reaction,it is believed that this polymer had end groups derived from4,4-dichlorobenzophenone.

EXAMPLE VII

A polymer of the formula ##STR73## wherein n represents the number ofrepeating monomer units was prepared as follows. A 500 milliliter,3-neck round-bottom flask equipped with a Dean-Stark (Barrett) trap,condenser, mechanical stirrer, argon inlet, and stopper was situated ina silicone oil bath. 4,4'-Dichlorobenzophenone (Aldrich 11,370, AldrichChemical Co., Milwaukee, Wis., 16.32 grams, 0.065 mol),bis(4-hydroxyphenyl)methane (Aldrich, 14.02 grams, 0.07 mol), potassiumcarbonate (21.41 grams), anhydrous N,N-dimethylacetamide (100milliliters), and toluene (100 milliliters) were added to the flask andheated to 175° C. (oil bath temperature) while the volatile toluenecomponent was collected and removed. After 48 hours of heating at 175°C. with continuous stirring, the reaction mixture was filtered and addedto methanol to precipitate the polymer, which was collected byfiltration, washed with water, and then washed with methanol. The yieldof vacuum dried product, poly(4-CPK-BPM), was 24 grams. The polymerdissolved on heating in N-methylpyrrolidinone, N,N-dimethylacetamide,and 1,1,2,2-tetrachloroethane. The polymer remained soluble after thesolution had cooled to 25° C.

EXAMPLE VIII

The polymer poly(4-CPK-BPM), prepared as described in Example VII, waschloromethylated as follows. A solution of chloromethyl methyl ether (6mmol/milliliter) in methyl acetate was prepared by adding acetylchloride (35.3 grams) to a mixture of dimethoxymethane (45 milliliters)and methanol (1.25 milliliters). The solution was diluted with 150milliliters of 1,1,2,2-tetrachloroethane and then tin tetrachloride (0.3milliliters) was added. After taking the mixture to reflux using an oilbath set at 110° C., a solution of poly(4-CPK-BPM) (10 grams) in 125milliliters of 1,1,2,2-tetrachloroethane was added. Reflux wasmaintained for 2 hours and then 5 milliliters of methanol were added toquench the reaction. The reaction solution was added to 1 gallon ofmethanol using a Waring blender to precipitate the product,chloromethylated poly(4-CPK-BPM), which was collected by filtration andvacuum dried. The yield was 9.46 grams of poly(4-CPK-BPM) with 2chloromethyl groups per polymer repeat unit. The polymer had thefollowing structure: ##STR74##

EXAMPLE IX

A polymer of the formula ##STR75## wherein n represents the number ofrepeating monomer units was prepared as follows. A 500 milliliter,3-neck round-bottom flask equipped with a Dean-Stark (Barrett) trap,condenser, mechanical stirrer, argon inlet, and stopper was situated ina silicone oil bath. 4,4'-Dichlorobenzophenone (Aldrich 11,370, AldrichChemical Co., Milwaukee, Wis., 16.32 grams, 0.065 mol),hexafluorobisphenol A (Aldrich, 23.52 grams, 0.07 mol), potassiumcarbonate (21.41 grams), anhydrous N,N-dimethylacetamide (100milliliters), and toluene (100 milliliters) were added to the flask andheated to 175° C. (oil bath temperature) while the volatile toluenecomponent was collected and removed. After 48 hours of heating at 175°C. with continuous stirring, the reaction mixture was filtered and addedto methanol to precipitate the polymer, which was collected byfiltration, washed with water, and then washed with methanol. The yieldof vacuum dried product, poly(4-CPK-HFBPA), was 20 grams. The polymerwas analyzed by gel permeation chromatography (gpc) (elution solvent wastetrahydrofuran) with the following results: M_(n) 1,975, M_(peak)2,281, M_(w) 3,588, and M_(z+1) 8,918.

EXAMPLE X

The polymer poly(4-CPK-HFBPA), prepared as described in Example IX, ischloromethylated by the process described in Example VIII. It isbelieved that similar results will be obtained.

EXAMPLE XI

A polymer of the formula ##STR76## wherein n represents the number ofrepeating monomer units was prepared as follows. A 1-liter, 3-neckround-bottom flask equipped with a Dean-Stark (Barrett) trap, condenser,mechanical stirrer, argon inlet, and stopper was situated in a siliconeoil bath. 4,4'-Difluorobenzophenone (Aldrich Chemical Co., Milwaukee,Wis., 43.47 grams, 0.1992 mol), 9,9'-bis(4-hydroxyphenyl)fluorenone (KenSeika, Rumson, N.J., 75.06 grams, 0.2145 mol), potassium carbonate(65.56 grams), anhydrous N,N-dimethylacetamide (300 milliliters), andtoluene (52 milliliters) were added to the flask and heated to 175° C.(oil bath temperature) while the volatile toluene component wascollected and removed. After 5 hours of heating at 175° C. withcontinuous stirring, the reaction mixture was allowed to cool to 25° C.The solidified mass was treated with acetic acid (vinegar) and extractedwith methylene chloride, filtered, and added to methanol to precipitatethe polymer, which was collected by filtration, washed with water, andthen washed with methanol. The yield of vacuum dried product,poly(4-FPK-FBPA), was 71.7 grams. The polymer was analyzed by gelpermeation chromatography (gpc) (elution solvent was tetrahydrofuran)with the following results: M_(n) 59,100, M_(peak) 144,000, M_(w)136,100, M_(z) 211,350, and M_(z+1) 286,100.

EXAMPLE XII

A polymer of the formula ##STR77## wherein n represents the number ofrepeating monomer units was prepared as follows. A 1-liter, 3-neckround-bottom flask equipped with a Dean-Stark (Barrett) trap, condenser,mechanical stirrer, argon inlet, and stopper was situated in a siliconeoil bath. 4,4'-Dichlorobenzophenone (Aldrich Chemical Co., Milwaukee,Wis., 50.02 grams, 0.1992 mol), 9,9'-bis(4-hydroxyphenyl)fluorenone (KenSeika, Rumson, N.J., 75.04 grams, 0.2145 mol), potassium carbonate(65.56 grams), anhydrous N,N-dimethylacetamide (300 milliliters), andtoluene (52 milliliters) were added to the flask and heated to 175° C.(oil bath temperature) while the volatile toluene component wascollected and removed. After 24 hours of heating at 175° C. withcontinuous stirring, the reaction mixture was allowed to cool to 25° C.The reaction mixture was filtered and added to methanol to precipitatethe polymer, which was collected by filtration, washed with water, andthen washed with methanol. The yield of vacuum dried product,poly(4-CPK-FBP), was 60 grams.

EXAMPLE XIII

The polymer poly(4-CPK-FBP), prepared as described in Example XII, waschloromethylated as follows. A solution of chloromethyl methyl ether (6mmol/milliliter) in methyl acetate was prepared by adding acetylchloride (38.8 grams) to a mixture of dimethoxymethane (45 milliliters)and methanol (1.25 milliliters). The solution was diluted with 100milliliters of 1,1,2,2-tetrachloroethane and then tin tetrachloride (0.5milliliters) was added in 50 milliliters of 1,1,2,2-tetrachloroethane.After taking the mixture to reflux using an oil bath set at 100° C., asolution of poly(4-CPK-FBP) (10 grams) in 125 milliliters of1,1,2,2-tetrachloroethane was added. The reaction temperature wasmaintained at 100° C. for 1 hour and then 5 milliliters of methanol wereadded to quench the reaction. The reaction solution was added to 1gallon of methanol using a Waring blender to precipitate the product,chloromethylated poly(4-CPK-FBP), which was collected by filtration andvacuum dried. The yield was 9.5 grams of poly(4-CPK-FBP) with 1.5chloromethyl groups per polymer repeat unit. When the reaction wascarried out at 110° C. (oil bath set temperature), the polymer gelledwithin 80 minutes. The polymer had the following structure: ##STR78##

EXAMPLE XIV

A polymer of the formula ##STR79## wherein n represents the number ofrepeating monomer units was prepared as follows. A 1-liter, 3-neckround-bottom flask equipped with a Dean-Stark (Barrett) trap, condenser,mechanical stirrer, argon inlet, and stopper was situated in a siliconeoil bath. 4,4'-Difluorobenzophenone (Aldrich Chemical Co., Milwaukee,Wis., 16.59 grams), bisphenol A (Aldrich 14.18 grams, 0.065 mol),potassium carbonate (21.6 grams), anhydrous N,N-dimethylacetamide (100milliliters), and toluene (30 milliliters) were added to the flask andheated to 175° C. (oil bath temperature) while the volatile toluenecomponent was collected and removed. After 4 hours of heating at 175° C.with continuous stirring, the reaction mixture was allowed to cool to25° C. The solidified mass was treated with acetic acid (vinegar) andextracted with methylene chloride, filtered, and added to methanol toprecipitate the polymer, which was collected by filtration, washed withwater, and then washed with methanol. The yield of vacuum dried product,poly(4-FPK-BPA), was 12.22 grams. The polymer was analyzed by gelpermeation chromatography (gpc) (elution solvent was tetrahydrofuran)with the following results: M_(n) 5,158, M_(peak) 15,080, M_(w) 17,260,and M_(z+1) 39,287. To obtain a lower molecular weight, the reaction canbe repeated with a 15 mol% offset in stoichiometry.

EXAMPLE XV

4'-Methylbenzoyl-2,4-dichlorobenzene, of the formula ##STR80## wasprepared as follows. To a 2-liter flask equipped with a mechanicalstirrer, argon inlet, Dean Stark trap, condenser, and stopper andsituated in an oil bath was added toluene (152 grams). The oil bathtemperature was raised to 130° C. and 12.5 grams of toluene wereremoved. There was no indication of water. The flask was removed fromthe oil bath and allowed to cool to 25° C. 2,4-Dichlorobenzoyl chloride(0.683 mol, 143 grams) was added to form a solution. Thereafter,anhydrous aluminum chloride (0.8175 mol, 109 grams) was addedportion-wise over 15 minutes with vigorous gas evolution of hydrochloricacid as determined by odor. The solution turned orange-yellow and thenred. The reaction was stirred for 16 hours under argon, and on removingthe solvent, a solid lump was obtained. The mass was extracted withmethylene chloride (1 liter), which was then dried over potassiumcarbonate and filtered. The filtrate was concentrated using a rotaryevaporator and a vacuum pump to yield an oil which, upon cooling, becamea solid crystalline mass. Recrystallization from methanol (1 liter) at-15° C. gave 82.3 grams of 4'-methylbenzoyl-2,4-dichlorobenzene (meltingpoint 55°-56° C.) in the first crop, 32 grams of product (from 500milliliters of methanol) in the second crop, and 16.2 grams of productin the third crop. The total recovered product was 134.7 grams in 65.6%yield.

EXAMPLE XVI

Benzoyl-2,4-dichlorobenzene, of the formula ##STR81## was prepared asfollows. To a 2-liter flask equipped with a mechanical stirrer, argoninlet, Dean Stark trap, condenser, stopper and situated in an oil bathwas added benzene (200 grams). The oil bath temperature as raised to100° C. and 19 grams of benzene were removed. There was no indication ofwater. The flask was removed from the oil bath and allowed to cool to25° C. 2,4-Dichlorobenzoyl chloride (0.683 mol, 143 grams) was added toform a solution. Thereafter, anhydrous aluminum chloride (0.8175 mol,109 grams) was added portion-wise over 15 minutes with vigorous gasevolution. Large volumes of hydrochloric acid were evolved as determinedby odor. The solution turned orange-yellow and then red. The reactionwas stirred for 16 hours under argon and was then added to 1 liter ofice water in a 2-liter beaker. The mixture was stirred until it becamewhite and was then extracted with methylene chloride (1 liter). Themethylene chloride layer was dried over sodium bicarbonate and filtered.The filtrate was concentrated using a rotary evaporator and a vacuumpump to yield an oil which, upon cooling, became a solid crystallinemass (154.8 grams). Recrystallization from methanol gave 133.8 grams ofbenzoyl-2,4-dichlorobenzene as white needles (melting point 41°-43° C.)in the first crop.

EXAMPLE XVII

2,5-Dichlorobenzoyl chloride was prepared as follows. To a 2-liter,3-neck round-bottom flask situated in an ice bath and equipped with anargon inlet, condenser, and mechanical stirrer was added2,5-dichlorobenzoic acid (93.1 grams) in 400 milliliters ofdichloromethane to form a slurry. Thionyl chloride (85 grams) in 68grams of dichloromethane was then added and the mixture was stirred at25° C. The mixture was then gradually heated and maintained at refluxfor 16 hours. Thionyl chloride was subsequently removed using a Claisendistillation take-off head with heating to greater than 80° C. Thereaction residue was transferred to a 500 milliliter 1-neck round bottomflask and then distilled using a Kugelrohr apparatus and a vacuum pumpat between 70° and 100° C. at 0.1 to 0.3 mm mercury to obtain 82.1 gramsof 2,5-dichlorobenzoyl chloride, trapped with ice bath cooling as ayellow-white solid.

EXAMPLE XVIII

Benzoyl-2,5-dichlorobenzene, of the formula ##STR82## was prepared asfollows. To a 2-liter flask equipped with a mechanical stirrer, argoninlet, Dean Stark trap, condenser, and stopper and situated in an oilbath was added benzene(140 grams). The oil bath temperature was raisedto 100° C. and 19 grams of benzene were removed. There was no indicationof water. The flask was removed from the oil bath and allowed to cool to25° C. 2,5-Dichlorobenzoyl chloride (92.6 grams), prepared as describedin Example XVII, was added to form a solution. Thereafter, anhydrousaluminum chloride (0.8175 mol, 109 grams) was cautiously addedportion-wise over 15 minutes with vigorous gas evolution. Large volumesof hydrochloric acid were evolved as determined by odor. The solutionturned orange-yellow and then red. The reaction was stirred for 16 hoursunder argon and was then added to 1 liter of ice water in a 2-literbeaker. The mixture was stirred until it became white and was thenextracted with methylene chloride (1 liter). The methylene chloridelayer was dried over sodium bicarbonate and filtered. The filtrate wasconcentrated using a rotary evaporator and a vacuum pump to yieldcrystals (103.2 grams). Recrystallization from methanol gavebenzoyl-2,5-dichlorobenzene as white needles (melting point 85°-87° C.).

EXAMPLE XIX

4'-Methylbenzoyl-2,5-dichlorobenzene, of the formula ##STR83## wasprepared as follows. To a 2-liter flask equipped with a mechanicalstirrer, argon inlet, Dean Stark trap, condenser, and stopper andsituated in an oil bath was added toluene (200 grams). Thereafter,anhydrous aluminum chloride (64 grams) was cautiously added portion-wiseover 15 minutes with vigorous gas evolution. Large volumes ofhydrochloric acid were evolved as determined by odor. The solutionturned orange-yellow and then red. The reaction was stirred for 16 hoursunder argon and was then added to 1 liter of ice water in a 2-literbeaker. The mixture was stirred until it became white and was thenextracted with methylene chloride (1 liter). The methylene chloridelayer was dried over sodium bicarbonate and filtered. The filtrate wasconcentrated using a rotary evaporator and a vacuum pump to yieldcrystals. Recrystallization from methanol gave 37.6 grams of4'-methylbenzoyl-2,5-dichlorobenzene as light-yellow needles (meltingpoint 107°-108° C.).

EXAMPLE XX

A polymer of the formula ##STR84## wherein n represents the number ofrepeating monomer units was prepared as follows. A 250 milliliter,3-neck round-bottom flask equipped with a Dean-Stark (Barrett) trap,condenser, mechanical stirrer, argon inlet, and stopper was situated ina silicone oil bath. 4'-Methylbenzoyl-2,4-dichlorobenzene (0.0325 mol,8.6125 grams, prepared as described in Example XV), bis-phenol A(Aldrich 23,965-8, 0.035 mol, 7.99 grams), potassium carbonate (10.7grams), anhydrous N,N-dimethylacetamide (60 milliliters), and toluene(60 milliliters, 49.1 grams) were added to the flask and heated to 175°C. (oil bath temperature) while the volatile toluene component wascollected and removed. After 24 hours of heating at 175° C. withcontinuous stirring, the reaction product was filtered and the filtratewas added to methanol to precipitate the polymer. The wet polymer cakewas isolated by filtration, washed with water, then washed withmethanol, and thereafter vacuum dried. The polymer (7.70 grams, 48%yield) was analyzed by gel permeation chromatography (gpc) (elutionsolvent was tetrahydrofuran) with the following results: M_(n) 1,898,M_(peak) 2,154, M_(w) 2,470, M_(z) 3,220, and M_(z+1) 4,095.

EXAMPLE XXI

A polymer of the formula ##STR85## wherein n represents the number ofrepeating monomer units was prepared by repeating the process of ExampleXX except that the 4'-methylbenzoyl-2,4-dichlorobenzene startingmaterial was replaced with 8.16 grams (0.0325 mol) ofbenzoyl-2,4-dichlorobenzene, prepared as described in Example XVI, andthe oil bath was heated to 170° C. for 24 hours.

EXAMPLE XXII

The process of Example III is repeated except that the poly(4-CPK-BPA)is replaced with the polymer prepared as described in Example XX. It isbelieved that similar results will be obtained.

EXAMPLE XXIII

The process of Example III is repeated except that the poly(4-CPK-BPA)is replaced with the polymer prepared as described in Example XXI. It isbelieved that similar results will be obtained.

Other embodiments and modifications of the present invention may occurto those skilled in the art subsequent to a review of the informationpresented herein; these embodiments and modifications, as well asequivalents thereof, are also included within the scope of thisinvention.

What is claimed is:
 1. A polymer having terminal end groups and monomerrepeat units, at least some of said monomer repeat units havinghalomethyl substituents which enable crosslinking or chain extension ofthe polymer upon exposure to a radiation source which is electron beamradiation, x-ray radiation, or deep ultraviolet radiation, said polymerhaving monomer repeat units of the formula ##STR86## wherein x is aninteger of 0 or 1, X represents a halogen atom, a, b, c, and d are eachintegers of 0, 1, 2, 3, or 4, provided that at least one of a, b, c, andd is equal to or greater than 1 in at least some of the monomer repeatunits of the polymer, A is ##STR87## or mixtures thereof, B is ##STR88##wherein v is an integer of from 1 to about 20, ##STR89## wherein z is aninteger of from 2 to about 20, ##STR90## wherein u is an integer of from1 to about 20, ##STR91## wherein w is an integer of from 1 to about 20,##STR92## or mixtures thereof, and n is an integer representing thenumber of repeating monomer units.
 2. A polymer according to claim 1wherein the polymer contains at least about 0.5 halomethyl groups perrepeat monomer unit.
 3. A polymer according to claim 1 wherein thepolymer is substituted with halomethyl groups to a degree of least about0.8 milliequivalents per gram.
 4. A polymer according to claim 1 whereinA is ##STR93## and B is ##STR94## wherein z is an integer of from 2 toabout 20, or a mixture thereof.
 5. A polymer according to claim 1wherein the polymer has end groups derived from the "A" groups of thepolymer.
 6. A polymer according to claim 1 wherein the polymer has endgroups derived from the "B" groups of the polymer.
 7. A compositioncomprising a polymer according to claim 1 further containing asensitizer.
 8. A composition comprising a polymer according to claim 1further containing a photoinitiator.
 9. A composition comprising apolymer according to claim 1 further containing a solvent.